Introduction

In order to allow the "adiabatic" turbocompound engine to reach its full potential, new materials for certain components must be developed. Thick (>2 mm) ceramic surface coatings have an

1. Maintaining sufficient strength in the PSZ (Partially Stabilized Zirconia) coatings during operation in diesel engines. It requires:

- high temperature phase stability

- grain boundary characterization (is Si at the grain boundary of advantage or not?)

- addition of other oxides, e.g. both Mg0+y203, or Ce02 stabilizer

2. Toughening of PSZ coatings

- fiber or whisker reinforcement

- a rougher or thicker and more corrosion resistant bond coat

- spraying of zirconia with thinner passes (or graded grain size)

- spraying of zirconia at relative lew substrate temperature

(microcracking)

3. Sealing of the ceramic outer surfaces

- implantation of Cr/Cr^O^

- laser treatment of the Zr0„ surfaces with addition of Cr2®3

- metal outerlayers

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