Peening Action

When individual particles of shot in a high-velocity stream contact a metal surface, they produce slight, rounded depressions in the surface, stretching it radially and causing plastic flow of surface metal at the instant of contact. The effect usually extends to about 0.13 to 0.25 mm (0.005 to 0.010 in.) but may extend as much as 0.50 mm (0.02 in.) below the surface. The metal beneath this layer is not plastically deformed. In the stress distribution that results, the surface metal has induced...

D 09971 446 x 103 CHci 815 x 103 CFeCl2

Where D is expressed in g mL at 25 C (77 F) and the concentrations, C, of H2SO4, ferrous sulfate (FeSO4), HCl, and ferrous chloride (FeCl2) are expressed in g 100 mL. Equipment for the analysis of pickling solutions should be installed near the pickling operation to monitor acid concentration and to test the solutions at regular intervals. Testing after each acid addition and once or twice during an 8 h shift might be sufficient for batch operations. For continuous operations, which often...

11GS Reddy and P Taimsalu Trans Inst Met Finish Vol 47 1969 p 187193 Rhodium Plating

Rhodium in its solid form is hard (microhardness about 800 to 1000 HV) and tough. It is nearly as tarnish resistant as platinum and palladium. However, because of its rare occurrence in PGM ores and market speculation, it is much more expensive, limiting its engineering use. Like silver, it has one of the highest reflectivities of all metals, making it ideal for use as a counterpoint to cut diamonds in jewelry and as a nontarnishing reflective coating for mirrors. Its excellent wear resistance...

Operating and Maintaining the Degreaser

An effective operator training program and a routine maintenance program are important to safe and efficient vapor degreasing. Proper education and maintenance practices can greatly extend working life with assurance of smooth production. Following the checklist provided below should aid in beginning an efficient degreasing operation. Be sure the degreaser operator is adequately trained and equipped with the appropriate safety equipment and clothing. For emergency situations, such as power...

Introduction

PULSED-LASER DEPOSITION (PLD) is a physical vapor deposition (PVD) technique that has gained popularity for the growth of high-quality multicomponent oxide thin films (Ref 1, 2, 3). Conceptually, PLD is an extremely simple PVD technique. The output of a short laser pulse (10 to 30 ns) is focused onto a solid target. The laser rapidly raises the surface temperature of a small portion of the target well beyond the vaporization temperature. A plume of evaporated material is ejected from the target...

Applications

Wear-, erosion-, and corrosion-resistance applications extensively utilize CVD coatings, as do applications that require low friction characteristics. Table 2 lists the properties of typical CVD coating materials for these applications. Some materials, such as titanium diboride, titanium carbide, and silicon carbide, provide extremely low wear rates. Table 3 lists specific production applications for the wear-, erosion-, and corrosion protection provided by CVD coatings. Table 2 Selected wear...

ReF6 3H2 Re 6HF

The reaction temperature ranges from 500 to 900 C (930 to 1650 F). The best deposits are obtained at 700 C (1290 F) and at low pressure (< 2.7 kPa, or 20 torr). Another common reaction is the pyrolysis of the chloride The reaction temperature ranges from 1000 to 1250 C (1830 to 2280 F). The best deposits are obtained at low pressure (< 2.7 kPa, or 20 torr). This reaction usually gives a more ductile and purer material than the reaction given in Eq 4, although a higher temperature is...

Quality Control

Once a coating has been chosen for production, it is necessary to ensure that future supplies of the coating are consistent from batch to batch, maintaining satisfactory application properties, appearance, stability, and performance characteristics. Only by so doing can production quality be maintained. Testing can be costly consequently, quality control programs should be designed using the simplest test methods and the least number of tests necessary to ensure essential quality levels....

Electrophoresis

Electrophoresis is the migration of electrically charged particles suspended in a colloidal solution under the influence of an applied electric field. Deposition occurs at one of the electrodes where the charge on the particle is neutralized. The particles acquire a static charge during milling, or they can be charged artificially by absorption of certain additives or electrolytes. This coating process, now being used commercially with increasing frequency, is applicable to practically all...

Types of Electrolytes

Tin can be deposited from either alkaline or acid solutions. Electrolyte compositions and process operating details are provided in Ref 1, 2, and 3, as well as in publications of the International Tin Research Institute. Table 2 gives the basic details of electrolyte composition and operating conditions for alkaline solutions, and Tables 3 and 4 provide this information for acid solutions. Tin ions in the alkaline electrolytes have a valence of +4, whereas those in the acid electrolytes have a...

2SnOH4 SnOHii Sn 20H

This tin will codeposit with tin from the stannate ions, causing the rough spongy deposits mentioned above. In the alkaline systems, two factors tend to restrict the usable current density range and limit the deposition rate. One factor is the solubility of the stannates in hydroxide solutions. With the sodium formula, the normal increase is not possible, because sodium stannate is one of the unusual salts that have a reverse temperature coefficient of solubility. An example of this process is...

Surface Preparation

After the selection of a coating system, the most important factor to be considered is surface preparation. Surface preparation must be compatible with the primer and topcoating. Surface preparation is often the most costly phase of the corrosion prevention process for steel, averaging over half the cost of paint application exclusive of scaffolding. Surface preparation should remove mill scale, rust, oil, grease, atmospheric materials, weld spatter, and old coatings. Surface preparation also...

Lapping and Polishing

Lapping and polishing are used to produce smooth or ultrasmooth surfaces (i.e., surfaces with an R of a few nanometers). They are carried out by placing a slurry of abrasive particles in a liquid vehicle between the specimen and a hard metallic block (lapping) or a soft, flexible pad (polishing). While the block is loaded against the workpiece (specimen) either hydraulically or mechanically, the abrasive particles roll or slide across the specimen so that the wear process is one of three-body...

Single Wavelength Ellipsometry SWE

Ellipsometry was first practiced by Paul Drude (Ref 10) just prior to 1890. The name ellipsometry was introduced by A. Rothen (Ref 11) in 1945. Clearly, this is not a recently developed technique. Ellipsometry uses monochromatic light, optical elements that change the polarization state of the light, some sort of detector, and some calculation facilities. Although rudimentary forms of these requirements have been present throughout this century, the development of the photomultiplier, the...

Process Limitations

The principal limitations of the vapor degreasing process are related to the materials it can clean without damaging effects and the soils it can remove effectively. Size and shape of workpieces, quantity of work, and degree of cleanness obtainable may also limit the applicability of vapor degreasing, but to a lesser extent. Normally, these variables merely determine the degreaser design selected. Materials. All common industrial metals can safely be degreased with a minimum of difficulty,...

Solutions for Stripping Cadmium Plate

Electrodeposited cadmium can be stripped chemically from the basis metal by immersion in one of the following solutions ammonium nitrate, inhibited hydrochloric acid, chromic acid with a sulfuric acid addition, and ammonium persulfate with an ammonium hydroxide addition. Electrolytic stripping is performed in a solution of sodium cyanide with an addition of sodium hydroxide. Compositions of these stripping solutions, and the immersion times to be used with them, are given in Table 12. Table 12...

Mechanical Cleaning and Finishing

Mechanical cleaning and finishing methods most commonly employed for processing iron castings include abrasive blast cleaning (the most commonly used method for cleaning cast irons), abrasive waterjet cleaning and finishing, vibratory finishing, barrel finishing, and shot peening. Blast cleaning of castings is a process in which abrasive particles are propelled at high velocity to impact the casting surface and thereby forcefully remove surface contaminants. The contaminants are usually...

Classification of Stainless Steels

Stainless steels can be divided into five families. Four are based on the characteristic crystallographic structure microstructure of the alloys in the family ferritic, martensitic, austenitic, or duplex (austenitic plus ferritic). The fifth family, the precipitation-hardenable alloys, is based on the type of heat treatment used, rather than microstructure. Ferritic stainless steels are so named because their body-centered-cubic (bcc) crystal structure is the same as iron at room temperature....

Example

Normally, abrasive blasting would be the preferred method for removing rust and scale from a rough ferrous metal casting like Part 11 in Fig. 1. Chilled iron shot or steel abrasives are usually the most economical abrasives for this purpose. Pickling is seldom used for descaling castings, such as cast iron, because smut is deposited and must be removed by another cleaning operation. Severe pitting is also likely to result. Salt baths have been successfully used for descaling ferrous castings,...

Post Treatments

A white film (sometimes called white rust or wet storage stain) may appear on zinc surfaces during storage or shipment. The film is found on material with newly galvanized, bright surfaces and especially in such areas as crevices between closely packed sheets and angle bars. Wet storage film can form if the surfaces come into contact with condensate or rainwater and the moisture does not dry quickly. Zinc surfaces that have developed a normal protective layer of...

14JR Hollahan and AT Bell Ed Techniques and Applications of Plasma Chemistry John Wiley 1974 Types of Pecvd Systems

As with thermal CVD reactors, PECVD systems can be either the hot-wall type, in which the reactor walls, the substrate, and the reactant gases are all at the same temperature, or the cold-wall type, in which only the substrate is heated to the desired temperature. In addition, PECVD reactors can be of direct or remote plasma type, where consideration is given to the plasma generation and what is coupled to this plasma. Numerous articles in the published literature (Ref 15, 16, 17, 18, 19, 20,...

Laser Surface Processing

High-power lasers have been used to process materials to improve their wear resistance since the late 1960s. Laser surface modification techniques that are used to improve the wear resistance of cast irons include transformation hardening, melting, and alloying. The processing conditions, examples of microstructures, wear characteristics, and applications associated with each technique are discussed in greater detail in Ref 13. Laser Transformation Hardening. The wear resistance of highly...

Equipment for Dry Blast Cleaning

Dry blast cleaning is probably the most efficient and environmentally effective method for abrasive cleaning and finishing. Proper ventilation helps maintain a clean work area. No settling ponds or chemical treatment are required. Dust collectors provide dust disposal that is clean and simple, using sealed containers. Dry-blast systems need only be kept dry and can be started and stopped with minimum startup or shutdown operations. Several types of equipment are available for dry blast...

Repair of Phosphate Coatings

Small parts that do not accept a satisfactory phosphate coating can easily be stripped, cleaned, and rephosphated. Large parts with a faulty coating or with a coating that is damaged in processing are less easily handled, and repair of the phosphated surface may be preferable to stripping and rephosphating. The simplest method is to sand the phosphate film until all defective coating is removed and clean, bare metal is exposed. A proprietary phosphating solution compounded for this application...

Nickel Cobalt

Some of the earliest solutions for bright nickel plating contained cobalt, formate, and formaldehyde additions, but with the development of modern bright nickel solutions based on organic addition agents only, the cobalt-containing solutions have fallen into disuse. Today, the cobalt additions are used when it is necessary to increase the hardness and strength of nickel plating, especially in electroforming applications. Advantages. Compared with nickel itself, nickel-cobalt alloys are harder...

7A Prange in Spectrochim Acta Vol 44B 1989 p 437

Tromp, and M.C. Reuter, in Thin Solid Films, No. 236, 1993, p 140 Electron Spectroscopies (AES and XPS) AES and XPS determine the energies of electrons emitted from a surface. Those with specific energies usually are photoelectrons or Auger electrons. For detailed information, the reader is referred to Ref 3, 5, and 6. Principles for basic understanding are briefly characterized in the following and illustrated by some examples. X-ray Photoelectron Spectroscopy....

Salt Bath Descaling

The removal of oxide scale can be accelerated by using baths of molten sodium hydroxide (NaOH) to which certain reagents are added. These baths can be used with virtually all grades of stainless steel. Salt bath descaling has several advantages It acts only on the scale and does not result in metal loss or etching. It does not preferentially attack areas in which intergranular carbides are present. It is particularly useful in descaling the straight chromium grades without the preliminary...

Hot Dip Galvanizing

Hot dip galvanizing is a process in which an adherent, protective coating of zinc and iron-zinc alloys is developed on the surfaces of iron and steel products by immersing them in a bath of molten zinc. Most zinc coated steel is processed by hot dip galvanizing. In general, steels with the following maximum alloying impurity levels are best suited to galvanizing 0.05 Si, 0.05 P, 0.25 C, and 1.3 Mn. Batch Galvanizing. One method of hot dip galvanizing is the batch process, which is used for...

Eq

Where T T(z, t) is the temperature of the workpiece, t is time, and R is the fraction of the generated heat that flows into the workpiece. The solution to this boundary value problem is (Ref 17) where erfc is the complementary error function. On the surface Assuming that at a particular point on the surface the heat is applied beginning at x -a, the time of heating for a point on the surface is t (a - x)IV and the temperature at a point on the surface is The form of this analysis is consistent...

Chromating Mechanism

Next to the alkali metals, the metals that chromate coatings must protect against corrosion (i.e., aluminum, magnesium, zinc, and cadmium) are the most active metals in the periodic table. In fact, from the large negative standard electrode reduction potentials for aluminum and magnesium dissolution, one would expect these metals to dissolve when immersed in water. This does not occur, of course upon exposure to water or air, these metals immediately form a hydrated oxide film that is itself...

Methods of Application

Rust-preventive compounds are applied by Spraying or fogging electrostatically The type of rust preventive and the quantity, size, complexity, and surface finish of the articles to be coated will determine which method should be used. The equipment and methods of application are similar to those used in painting. Petrolatum compounds can be applied either hot or cold. Generally, cold application is restricted to parts that are either too large and bulky for practical tank immersion or require...

Powder Coating

Powder coatings are paint films that are applied to parts as a dry powder. The powders are basically the same type of polymers and resins (see Table 1) as used in liquid coatings except no solvent is used. Instead, the coating composition is ground to a fine powder. After application the film is formed by fusing the powder particles at temperatures above the melting point of the powder. Powder coatings are used on a wide range of products including metal furniture, wire goods such as baskets...

Types of Electroless Alloy Plating Systems

Most electroless alloy systems are based on nickel alloys and have been developed from basic electroless nickel-plating technology. Many alloy systems are documented in the literature and several are commercially available. In the following section each coating type is summarized and its availability is indicated as either production or laboratory. Nickel-Phosphorus. Electroless nickel-phosphorus is the most common nonelectrolytic alloy coating system. Electroless nickel has been used since the...

Cadmium Plating

Cadmium is primarily plated from a cyanide electrolyte. Acid cadmium baths are also used to a limited extent, and are fluoborate, sulfate, or chloride in nature. The acid-type baths are more desirable if hydrogen embrittlement is a problem, and their waste treatment is simplified. However, the cyanide baths are easier to control than the acid baths. Typical cadmium plating compositions are described in the article Cadmium Plating in this Volume. Applications and Properties....

Zn55Al Alloy Coatings

The purpose of Zn-55Al alloy coatings is to combine the excellent long-term atmospheric corrosion resistance of aluminum with the sacrificial characteristics of galvanized in a single coating (Ref 23, 24). Long-term studies showed that the 55 Al alloy was the optimum composition of the aluminum-zinc system. Steel sheet coated with this alloy was first produced commercially in 1972 in the United States under the trademark Galvalume. Coating thicknesses are usually in the range of 20 to 25 pm...

Problems and Corrective Procedures

Faulty operation of a chromium-plating solution can result in slow plating speed or deposits with undesirable characteristics. The problems encountered in hard chromium plating are similar for all three chemistries. Possible causes and suggested corrective procedures include Low ratio of chromic acid content to total catalyst content. Correct by adding chromic acid or by precipitating sulfate, if too high, with barium carbonate. Passive or scaled anodes. Correct by cleaning and reactivating...

Surface Hardening

Surface hardening is used to extend the versatility of certain steels by producing combinations of properties not readily attainable in other ways. For many applications, wear and the most severe stresses act only on the surface of a part. Therefore, the part may be fabricated from a formable low- or medium-carbon steel, and is surface hardened by a final heat treatment after all other processing has been accomplished. Surface hardening also reduces distortion and eliminates cracking that might...

Plating in High Efficiency Sodium and Potassium Cyanide Baths

High-efficiency sodium and potassium cyanide baths allow the use of higher current densities. Cyanide plating baths typically decrease in cathode efficiency, or speed of deposition, with increasing current, which accounts for the good plate distribution (throwing power). The cathode efficiency approaches 100 only at low current densities, often 10A dm2 or less. With more practical current densities of 2.0 to 3.0 A dm2, the cathode efficiency may drop 20 , especially with lower agitation rates....

High Precision Fixed Abrasive Finishing

A variety of high-precision processes have been in use, and new processes are constantly being developed to achieve extremely close geometric tolerances or to improve surface finish. The objective of all high-precision processes is to achieve geometrically precise components or surfaces of controlled texture or surface finish (Fig. 11). Table 5 compares the processes described in this section. A parallel set of processes using loose abrasives, called lapping, buffing, and polishing, are...

Group IIIV Semiconductor Growth Parameters

Group III-V semiconductors are the major materials used in optoelectronic and high-frequency electronic device applications. The ability to tailor the band structure and lattice constant in ternary and quaternary alloys by varying the composition represents one of the desirable features of these materials. The GaAs-based materials described below include not only GaAs, but gallium indium phosphide (GaInP), gallium aluminum arsenide (GaAlAs), and gallium indium arsenide phosphide (GaInAsP). GaAs...

Metallurgical Factors

A wide variety of metallurgical effects can occur during a finishing process formation of untempered or overtempered martensite, retained austenite, volume changes due to phase transformation, oxidation, and other effects can become important, depending on the mechanical and thermal aspects of the finishing operation. Reference 9 provides a good introduction to these phenomena in the case of grinding, while Ref 1 reviews various metallurgical alterations in the cases of milling, reaming,...

13DB Chrisey and GK Hubler Pulsed Laser Deposition of Thin Films Wiley 1994 General Description

In PVD of multicomponent thin films, the preparation of a stoichiometric vapor is often difficult to achieve. When singleelement sources are used, the arrival rate of each individual component must be calibrated and inter-regulated. In PLD, the composition of the vapor is the same as that of the target. Starting with the correct composition of the vapor greatly facilitates the growth of a desired phase in the depositing film. In addition, the absence of filaments or charged particles allows...

Organic Coatings

Paint is applied to a steel sheet or a part for one or both of the following reasons enhancement of the aesthetic value of the product and or preservation of structural integrity. The former goal is a consideration for the designer and will receive no further discussion in this section. The latter goal, however, will be discussed as it applies to prepainted steel. This section will describe how paints deter corrosion, the prepainting process, the primary differences between prepaint paint...

Anodizing Processes

The three principal types of anodizing processes are chromic processes, in which the electrolyte is chromic acid sulfuric processes, in which the electrolyte is sulfuric acid and hard anodic processes that use sulfuric acid alone or with additives. Other processes, used less frequently or for special purposes, use sulfuric acid with oxalic acid, phosphoric acid, oxalic acid, boric acid, sulfosalicylic acid, sulfophthalic acid, or tartaric acid. Except for thicker coatings produced by hard...

Nickel Anode Materials

Most nickel plating processes are operated with soluble nickel anode materials. Nickel from the anode is converted into ions that enter the plating solution to replace those discharged at the cathode. In addition, the anode distributes current to the parts being plated and influences metal distribution. The simplest way to satisfy anode requirements is to suspend nickel bars from hooks placed on an anode bar so that the nickel, not the hook, is immersed in the plating solution. Nickel anode...

Characteristics of Copper Plate

Variations in processing during surface preparation or during plating have significant effects on the quality of the copper electrodeposit. Certain variations can adversely affect the adhesion of copper to the substrate metal. Variations also can affect brightness, porosity, blistering, roughness, hardness, solderability, and leveling. Brightness. Bright copper coatings are generally obtained by the addition of brighteners to the electrolyte, although buffing of the electrodeposited coating...

Spindle Finishing Machines

Spindle finishing is categorized as a mass finishing process, although parts to be deburred or finished are mounted on fixtures. The process uses fine abrasive media for finishing. The spindle machine is a circular rotating tub that holds the abrasive media, and a rotating or oscillating spindle to which the part is fixed. The workpiece mounted on the spindle is immersed into the rapidly moving abrasive slurry, causing the abrasive to flow swiftly over rough edges and over the surfaces of...

Zinc Coatings

Hot-dip-zinc-coated steel sheet, also called galvanized, is by far the most widely used coated sheet product. About 86 of the hot-dip-coated sheet produced in the United States (see Fig. 1) is zinc coated. As evident in Table 1, hot dip zinc coatings for sheet are available in a broad range of coating thicknesses. For generalpurpose galvanized sheet, 19 pm (0.75 mil) per side is the usual thickness. This corresponds to a two-side coating mass of 275 g m2 (0.9 oz ft2). Heavier coatings are used...

Vapor Degreasing Equipment

All vapor degreaser designs provide for an inventory of solvent, a heating system to boil the solvent, and a condenser system to prevent loss of solvent vapors and control the upper level of the vapor zone within the equipment. Heating the degreaser is usually accomplished by steam. However, electrical resistance (< 3.0 W cm2 or < 20 W in.2) heaters, gas combustion tubes, and hot water can be used. Gas combustion heaters with open flames located below the vapor degreaser are not recommended...

Enameling Furnaces

Fusing of the porcelain enamel coating to its metal substrate or to a ground coat can be done in a continuous, intermittent, or batch furnace. The furnace may be heated by oil, natural gas, propane gas, or electricity. With oil heating, a muffle furnace is required to prevent the products of combustion from contaminating the enamel coating. Gas-fired furnaces are either muffle or radiant-tube, with a limited number of luminous-wall, direct-fired furnaces being used. Continuous furnaces are of...

Electrodischarge Machining

Electrodischarge machining (EDM) is a thermoelectric process that removes material from the workpiece by a series of discrete sparks between a work and tool electrode immersed in a liquid dielectric medium. The method of removal of material from the workpiece is by melting and vaporizing minute amounts of electrode material, which are then ejected and flushed away by the dielectric (Ref 1, 14). The two major types of EDM are die sinking EDM and wire EDM (WEDM). Die sinking EDM is traditionally...

13R Weil and K Sheppard Mater Char Vol 28 1992 p 103112

Bull, Surf Coat. Technol, Vol 39 40, 1989, p 315 Experimental Techniques for Microstructural Characterization It is not possible to determine all the structural features of a material using any one analysis technique. Therefore, many techniques that can be used to provide information about specific microstructural features have been developed. It is important to know what factors are important in any application before undertaking a program of structural analysis. For...

Process Capabilities

The thickness of mechanical plating deposits ranges from 5 to 75 pm (0.2 to 3 mils). The heavier coatings are referred to as mechanical galvanizing or cold-impact galvanizing coatings. Because the coating thickness is somewhat independent of cycle time and is controlled by the plating metal additions, a heavy galvanized coating thickness can be applied in almost as little time as thinner commercial coating thicknesses. Mechanical galvanizing provides uniform, smooth, and...

Hexavalent Chromium Plating

The first hexavalent chromium plating bath used for decorative plating, sometimes referred to as the conventional bath, consisted of an aqueous solution of chromic anhydride (CrO3) and a small amount of soluble sulfate (SO4 ), referred to as the catalyst. The latter was added as sulfuric acid or as a soluble sulfate salt, such as sodium sulfate. When dissolved in water, the chromic anhydride forms chromic acid, which is believed to exist in the following equilibrium The ratio of chromic acid to...

Advantages of Organic Acids

Although organic acids are relatively weak, they remove metal oxides through the following mechanisms. As the organic acid reacts with the metal to produce citrates, acetates and other byproducts, hydrogen gas is released. The hydrogen builds up under the scale and can often lift the remaining oxides off the metal. In addition, organic acids act as sequesterants by tying up the dissolved metal ions and carrying them away from the surface being cleaned. With the use of heated solutions and...

References cited in this section

Mattox, Particle Bombardment Effects on Thin-Film Deposition A Review, J. Vac. Sci. Technol. A, Vol 7 (No. 3), 1989, p 1105 15. J.M.E. Harper, J.J. Cuomo, R.J. Gambino, and H.R. Kaufman, Modification of Thin Film Properties by Ion Bombardment during Deposition, Chapter 4, Ion Bombardment Modification of Surfaces Fundamentals and Applications, O. Aucello and R. Kelly, Elsevier, 1984 16. D.M. Mattox, Adhesion and Surface Preparation, Chapter 3, Deposition Technologies for Films and...

CH3SiCl3 SiC 3HCl

The reaction temperature ranges from 900 to 1400 C (1650 to 2550 F), and pressure ranges from 1.3 to 6.7 kPa (10 to 50 torr) in a hydrogen atmosphere. The deposition rate and the crystallite size increase with the increasing partial pressure of MTS. Other precursor combinations are SiCl4 CH4, SiCl4 CCl4, SiH2Cl2 C3H8, and SiHCl3 C3H8, usually in a hydrogen atmosphere. Titanium carbide (Ref 33) is of major industrial importance in the coating of wear-resistant tools by the CVD process. The most...

4Techni Solder NF 1957 product data sheet Technic Inc Cranston RI Fluoborate Plating Solutions for Tin Lead

Any desired tin-lead alloy composition can be plated from a fluoborate solution. The composition of the deposit depends on the amount of stannous tin and lead in the solution, the type and amount of addition agent, the current density, and the tin-lead content of the anodes. Bath temperature and degree of agitation also affect the composition, especially in highspeed solutions. Solution Components. Concentrated solutions of stannous and lead fluoborates and fluoboric acid are available...

Surface Hardening of Ductile Iron

Ductile iron responds readily to surface hardening by flame, induction, or laser heating, or by nitriding. Because of the short heating cycle in these processes, the pearlitic types of ductile iron ASTM 80-60-03 and 100-70-03 are preferred. Irons without free ferrite in their microstructure respond almost instantly to flame or induction heating and require very little holding time at the austenitizing temperature in order to be fully hardened. With a moderate amount of free ferrite, the...

Cyanide Zinc Baths

Bright cyanide zinc baths may be divided into four broad classifications based on their cyanide content regular cyanide zinc baths, midcyanide or half-strength cyanide baths, low-cyanide baths, and microcyanide zinc baths. Table 1 gives the general composition and operating conditions for these systems. Table 1 Composition and operating conditions of cyanide zinc baths Table 1 Composition and operating conditions of cyanide zinc baths Mid or half-strength cyanide bath(b) Note Cathode current...

Vaporization Sources

Common heating techniques for evaporation sublimation include resistive heating, high-energy electron beams, low-energy electron beams, and inductive (radio frequency) heating. Figures 7, 8(a), and 8(b) show some vaporization source configurations. Resistive heating is the most common technique for vaporizing materialat temperatures below about 1800 C (3270 F), while focused electron beams are most commonly used above 1800 C (3270 F). Fig. 7 Sources used for resistive heating of materials in...

Flame Cleaning and Furnace Preparation

Sendzimir Oxidation Reduction Method. The original method for flame cleaning was proposed by Tadeusz Sendzimir in the 1930s. His invention involved heating a steel strip in a direct oxidizing flame to burn off the rolling oils and other contaminants. This step left an oxide on the steel surface, which was then cleaned by heating to a much higher temperature in a reducing furnace with a hydrogen-nitrogen atmosphere. This two-furnace cleaning method was converted into a coating line by cooling...

Spraying

Spraying is adaptable to either large-volume or low-volume production. Applications may be limited because of solvent emissions, possible fire hazards, or potential damage from overspray. Spraying methods include conventional air spraying, in which the paint is atomized and propelled against the work by means of compressed air, hot spraying, hydraulic airless spraying, and air and airless electrostatic spraying. Spraying is used for applications in which good appearance and uniformity of...

Sources of Depositing Species

The various thermal vaporization sources can be used in ion plating. For plasma-based ion plating, the resistively heated sources are most often used. Low-energy electron-beam heating from hollow cathode sources and thermionic sources can be used, often with a magnetic confining field. This allows the electrons to heat the material to be vaporized and also to create the plasma. High-energy electron-beam heating can be used, but this requires isolating the electron-emitting...

Removal of Residues from Magnetic Particle and Fluorescent Penetrant Inspection

Successful removal of the iron oxide particles deposited on ferrous parts during magnetic particle inspection requires complete demagnetization of the part. After demagnetization, emulsion cleaning is an effective and practical means of removing both the iron oxide residues and oil. Fluorescent pigments used for similar inspection of aluminum parts can be removed with hot alkaline cleaners. For low-to-moderate production, an efficient procedure consists of immersing parts in a light, undiluted,...

16JR Treglio AJ Perry and RJ Stinner Surface and Coatings Technology Vol 65 1994 p 184 Applications

Table 2 outlines some of the research and development applications that have been pursued using directed beam ion implantation technology. Of the properties listed, the tribological aspects of ion implantation have received the most attention (Ref 17). In spite of the relatively shallow penetration of implanted ions (typically nitrogen), implanted surfaces have often demonstrated a high degree of resistance to wear under mild abrasive or lubricated sliding conditions. This wear resistance is...

4HF H3BO3 HBF43H2OEq 6

Where HBF4is the resultant fluoboric acid. The reaction is reversible if the stoicheiometric amount of boric acid (H3BO3)is used to react with the hydrofluoric acid (HF) present. As the amount of boric acid in the above reaction is increased, the reaction is driven far to the right so that the reaction becomes irreversible and no free hydrofluoric acid is regenerated. This is important because if free hydrofluoric acid were present, then insoluble fluorides, especially lead fluoride, would...

Thermal Spray Coatings

Thermal spray coatings are surface coatings engineered to provide original equipment with resistance to wear, erosion, abrasion, corrosion, and oxidation. Thermal spraying is also used to repair and upgrade in-service equipment. In general, thermal spray coatings can be applied to a range of substrate materials, including metals, ceramics, plastics, and polymer composites. Such coatings often are used instead of paint because of their predictable service life, increased effectiveness, and lower...

Growth of Nuclei

When atoms condense they form nuclei. If the surface is of the same material as the depositing atoms, the process is called homogeneous nucleation if they are of different materials, the process is call heterogeneous nucleation. In semiconductor terminology, heterogeneous nucleation forms heterojunctions. Three types of nucleation mechanisms have been identified they differ according to nature of interaction between the deposited atoms and the substrate material (Ref 23) (a) the van der Merwe...

Hydrogen Embrittlement

If an electrodeposited coating is to be applied to a highly stressed part or a high-strength (over 1100 MPa, or 160 ksi) heat-treated steel part, it is important that the processing not decrease the static or fatigue strength of the part. Hydrogen embrittlement does not affect fatigue life. Coatings having high residual stresses, such as chromium, affect fatigue life however, this is not the case with cadmium. Cadmium deposited from a cyanide solution is more likely to produce hydrogen...

ECM Equipment

Figure 2 shows a schematic representation of the ECM system for finishing of a die or other complex shapes. The major components include the workpiece, cathode tool, electrolyte, power supply, and electrolyte circulating and purification system. A low voltage (8 to 30 V) is normally applied across the electrodes. A small gap (0.2 to 1 mm) is maintained between them, producing a current density of the order of 10 to 100 A cm2 (Ref 1, 2, 3). The electrolyte is forced through the small gap between...

Operating Parameters of Standard Cyanide and Midcyanide Zinc Solutions

Almost every physical form of zinc anode material has been used in cyanide zinc plating, the type and prevalence varying from country to country. In the United States, cast zinc balls approximately 50 mm (2 in.) in diameter, contained in spiral steel wire cages, are by far the most common anode material. A practical variation of this is the so-called flat top anode, with a flat surface to distinguish it from cadmium ball anodes. The use of ball anodes provides maximum anode area, ease...

Carburizing Boriding and Flame Hardening

Carburizing is a case-hardening process in which carbon is dissolved in the surface layers of a steel part at a temperature sufficient to render the material austenitic, followed by quenching and tempering to form a martensitic microstructure. The resulting gradient in carbon content below the surface of the part causes a gradient in hardness, producing a strong, wear-resistant surface layer. In gas carburizing, commercially the most important variant of carburizing, the source of carbon is a...

Grinding

A wide variety of abrasive finishing processes termed grinding are practiced in the finishing of industrial components. They offer the following advantages (compared to machining processes that use defined cutting edges) The range of surface geometries generated (e.g., contours, profiles, etc.) is frequently more complex than is economically possible in single-point machining processes. Grinding wheels can be used for high stock removal (i.e., rough grinding). The same wheel is often modified...

Environmental Impact

Most cleaning salts are formulated from alkali metal salts, as previously described. Some of these ingredients may be highly alkaline and corrosive. Process chemicals formulated for salt bath cleaning applications do not contain restricted or heavy metals in their fresh condition. The byproducts or sludge that must be removed from an operating bath will contain the materials that were processed in it. For example, byproducts formed from paint stripping applications will contain heavy metals if...

Curtain Coating

Gravity Changing Machine

Curtain coating is a method of applying finishes at high speeds with little paint loss. In curtain coating, flat or shaped strip and sheet are moved by conveyor belt beneath a pump-fed reservoir with an adjustable slot opening at its lower edge. The slot opening provides a controlled continuous wet curtain of coating flowing onto the work. Some curtain coaters have heads that function by use of gravity overflow of material over one side of the reservoir. The pressure-fed curtain coater applies...

Plating in Pyrophosphate Baths

Copper pyrophosphate plating baths offer a number of desirable features. Copper pyrophosphate forms a highly soluble and conductive complex when dissolved in potassium pyrophosphate solution. Potassium salts are preferred because of their higher solubilities. Copper pyrophosphate plating baths operate at nearly 100 cathode efficiency and provide good throwing power. They are noncorrosive because the operating pH is near neutral. Concentration limits and operating conditions for copper...

Control of Crystal Size

The crystalline structure of the chemically bonded phosphate coating (Fig. 11) provides a suitable base for subsequent paint or oil films. Crystals permit the paint to penetrate, providing the paint with exceptional adherence. When oil is the rust preventive, the interstices of the crystalline structure function efficiently as an oil-retaining reservoir. The adhesion of phosphate coating to the base metal, as determined by flexing of the metal, varies with the type and thickness of the coating....

Application Of Electroplating In Civil Engineering

CONTINUOUS ELECTRODEPOSITION involves electroplating a pure metal or alloy coating onto an endless steel strip. In practice, this is achieved by unwinding a coil of strip welding it to the tail end of the preceding coil passing it through the sequence of surface preparation, electroplating, and surface post-treatment rewinding it and then again cutting it from the preceding coil. The facilities used for this process are commonly called continuous plating lines and can handle strip of up to...

Equipment

The equipment used in shot peening is essentially the same as that used in abrasive blast cleaning, except for certain auxiliary equipment made necessary by the more stringent controls imposed in the shot peening process. For a description of basic equipment, such as cabinets, wheels, nozzles, and conveyors, see the article Mechanical Cleaning Systems in this Volume. The principal components of shot peening equipment are a shot-propelling device, shot recycling and classification arrangements,...

Acid Descaling Pickling

Acid descaling, or pickling, is the removal of heavy, tightly adherent oxide films resulting from hot-forming operations, thermal treatments (such as annealing or hardening), or welding (Ref 4). Because most stainless steel products received from the producing mill have been pickled, descaling is required only as a result of subsequent manufacturing operations. In evaluating the different methods for removing scale, it should be kept in mind that scale on stainless steel is far more complex...

Crack Patterns and Other Characteristics of Hard Chromium Plate

The quality of hard chromium plate is evaluated chiefly from the standpoint of thickness and thickness distribution, appearance, crack pattern, crack size, porosity, roughness, and adhesion of the plate to the base metal. Surface Cracks. During the deposition of chromium deposits, microcracks form to relieve the internal stress. These cracks subsequently fill in with plated chromium. The chromium in these former cracks is more easily etched and has a different refractive index than the...

Phosphate Coating

Phosphate coating is the treatment of bare or galvanized steel with a dilute solution of phosphoric acid and other chemicals in which the surface of the metal, reacting chemically with the phosphoric acid medium, is converted to an integral, mildly protective layer of insoluble crystalline phosphate. Phosphate conversion coatings are applied to steel substrates to enhance corrosion resistance, increase paint adhesion, or both. Phosphate coatings range in thickness from less than 3 to 50 pm (0.1...

Racks and Fixtures

The following recommendations are offered regarding the design and use of plating racks Racks should be designed to hold workpieces in a favorable position for plating uniformly on significant surfaces and to facilitate racking and unracking. Workpieces with protruding sections should be racked so that parts shield each other. If this is not possible, a current thief should be used to reduce current density at the protruding points. Electrical contact with the part should be made on an...

Anodizing Equipment and Process Control

Low-carbon steel tanks are satisfactory for chromic acid baths. It is common practice to line up to half of the tank with an insulating material, such as glass, to limit the cathode area with respect to the expected anode area (a 1-to-1 ratio is normal). The cathode area need only be 5 of the maximum anode area. In nonconducting tanks, suitable cathode area is provided by the immersion of individual lead cathodes however, these require the installation of additional...

Quality Control of Nickel Plating

Achieving high quality involves controlling the bath composition, the purity of the plating solution, and the thickness and uniformity of the deposits. Eliminating rejects, troubleshooting, and the testing of deposits are important aspects of process and product control. Control of Solution Composition. Control of the composition of the plating bath is one of the most important factors contributing to the quality of nickel deposits. At the outset, the bath must be prepared to the specified...

Reference cited in this section

Modification and Repair for Printed Boards and Assemblies, Manual IPC-R700B, Institute for Interconnecting and Packaging Electronic Circuits Health and Safety Considerations There are two safety issues in selective plating the chemicals and the equipment used to apply the chemicals. Overall, the process meets the safety requirements set by the Occupational Safety and Health Administration (OSHA) for in-plant use. Electrical protection of the power pack, workpiece, and operator are provided by a...

Calculating Coating Coverage and Costs

The cost of the applied coating is directly related to the cost per gallon of coating material, the application efficiency, the required thickness of film, and the spreading rate. To calculate the gallons needed and cost for coating an object the following information is needed. Volume of solids in coating Spreading rate of coating at application viscosity Dry film thickness required Volume solids content of the coating is the volume percentage of vehicle solids and pigments in a gallon of...

Anodes

Lead of satisfactory purity for anodes may be obtained either as corroding lead or chemical lead. Chemical lead anodes generally are preferred. Impurities in the anodes such as antimony, bismuth, copper, and silver cause the formation of anode slime or sludge and can cause rough deposits if they enter the plating solution. These impurities can also cause anode polarization if present in the anode, especially at higher anode current densities. Small amount of tin and zinc are not harmful. Anode...

Zinc Cobalt Plating

Zinc-cobalt coatings contain 0.6 to 2 Co. Zinc-cobalt alloys find extensive use for relatively inexpensive components in applications that require improved abrasion resistance and corrosion protection. Typically, an 8 pm film with 1 cobalt will last up to 500 h in a neutral salt spray test before red rust if the proper chromate is applied. Some reduction in corrosion resistance is experienced after exposure to high temperature, but not as much as with zinc-iron alloys. A unique attribute of...

Example 1 Residual Stresses in Grinding

The existence of residual stresses in a ground specimen is due to the combined action of mechanical and thermal effects. Mechanical Effect. Mechanical forces during grinding expand the surface of a sample, so that the plastically deformed surface experiences a compressive residual stress state while the elastically deformed near-surface layer is left in a state of residual tension. The elevation of temperature in the surface of the sample as a result of the cutting action causes a reduction in...

Removal of Unpigmented Oil and Grease

Common shop oils and greases, such as unpigmented drawing lubricants, rust-preventive oils, and quenching and lubricating oils, can be effectively removed by several different cleaners. Selection of the cleaning process depends on production flow as well as on the required degree of cleanness, available equipment, and cost. For example, steel parts in a clean and dry condition will rust within a few hours in a humid atmosphere. Thus, parts that are thoroughly clean and dry must go to the next...

MOCVD Starting Materials

The alkyls of Group II and III metals and the hydrides of Group V and VI elements are generally used as precursors in MOCVD. Dilute vapors of these chemicals are transported at or near room temperature to a hot zone, where pyrolysis reactions occur. For example, GaAs is formed by heating trimethylgallium, (CH3)3Ga, or triethylgallium, (C2H5)3Ga, and AsH3 over a suitable substrate, usually a single crystal of GaAs or silicon, at temperatures near 600 C (1110 F). The decomposition reactions can...

Ruthenium Plating

Ruthenium in the solid form is hard and brittle furthermore, it oxidizes rather easily. These factors limit its use, even as its low price relative to the other PGMs provides impetus for its application. Despite extensive research work on electroplating of ruthenium, it has obtained a small market share in only two areas for decorative applications such as eyeglass frames and for layers on electrical contacts used in sealed atmospheres. All ruthenium plating electrolytes are based on solutions...

Components of Continuous Steel Strip Plating Lines

Figures 6, 7, 8, and 9 show schematic diagrams of continuous steel electroplating lines for tin, chromium, and zinc coatings. Figure 9 may be consulted in the following discussion of the general features of these lines. The line in Fig. 9 is also designed for painting over the metallic coated strip, which for economic reasons may become the trend, particularly for zinc and zinc alloy coating lines whose lower speeds can allow roll coating of the organic films. Fig. 6 Schematic diagram of a...

Color Anodizing

Dyeing consists of impregnating the pores of the anodic coating, before sealing, with an organic or inorganic (e.g., ferric ammonium oxalate) coloring material. The depth of dye adsorption depends on the thickness and porosity of the anodic coating. The dyed coating is transparent, and its appearance is affected by the basic reflectivity characteristics of the aluminum. For this reason, the colors of dyed aluminum articles should not be expected to match paints, enamel, printed fabrics, or...

Dip Painting

Dip painting consists of submerging a part in paint contained in a tank, withdrawing the part, and permitting the part to drain. Parts with complex surfaces may be coated efficiently by dipping. Larger parts, produced in quantity, are racked or hung on conveyors, which carry the parts to the paint tank, automatically immerse and withdraw the parts, and carry them over drip troughs into which the excess paint runs off. Dip painting is seldom used where uniformity of paint thickness is required....

Group IV Semiconductor Growth Parameters

Silicon is the foundation of the present electronics industry. Epitaxial layers are used routinely in high-performance CMOS and bipolar technologies. Not surprisingly, the CVD process for silicon is the most mature. Germanium is another important Group IV semiconductor. Because both of these materials are grown from either chloride or hydride sources, they are categorized as CVD, rather than MOCVD, processes. Epitaxial silicon (Si) layers can be grown at atmospheric pressure in the temperature...

Kinetics and Gas Phase Transport

Thermodynamics determine the state of a closed system at equilibrium and indicate what to expect from the reactants on a surface (substrate) at a given temperature. However, the MOCVD process is not, by definition, an equilibrium process. Thermodynamics can only define certain limits for the growth process. It is not possible to use thermodynamics to predict the time required to attain equilibrium, what steps to take to achieve the lowest energy state, or the rates at which various processes...

Paint Stripping

Infrequently, parts have to be stripped and repainted. Possibly there is a problem with appearance the wrong paint or color may have been used. Tools, fixtures, and automatic spray line fixtures must be periodically cleaned of old paint buildup as well. Some paints are easier to strip than others, and some paint stripping methods are incompatible with some metals. A hot alkaline cleaning bath, which is a part of a metal process line, should not be used as a paint stripping tank. Even if the...