Experimental Plan

The work plan for this program was organized into three tasks as outlined in Table 1. In Task I, transformation toughened Zr02 ceramics were identified for evaluation and study. At the time the study was initiated, six partially stabilized zirconias (PSZ) and two zirconia toughened aluminas (ZTA) were available commercially. All eight of these materials were purchased for evaluation. A list of the candidate materials obtained and a brief description of these materials is presented in Table 2. Characterization studies to determine flexure strength, fracture toughness, hardness, and thermal coefficient of expansion were conducted on these materials.

From the eight initial materials, five were selected for further study in Task II of the program. In this task, flexure . strengths from 20°C to 1050°C were measured

Table 1. Work Scope

Task I

Task II

Task III

Evaluation of Potential Candidate Transformation Toughened Ceramics (TTC)

• Identification of TTC Suppliers

• Screening Evaluation of Potential Candidate TTC Materials

• Analysis of TTC Screening Data

Investigation of five

Selected Candidate


• Finalize Candidate Selection for Matrix Testing Plan (four temperatures, two atmospheres, and two stressing rates)

t Conduct Candidate Matrix Test Program

• Conduct Aging Studies

Detailed Investigation of the Two Finalist TTC Materials

• Selection of the Two Finalist Materials

• Finalization of an Expanded Matrix Testing Plan

• Implementation of MOR Testing Plan

Table 2. Candidate Transformation Toughened Ceramics

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