Nanocrystalline 70 wt. % Ni–30 wt.% Fe alloy powders were synthesized by spray pyrolysis from a solution of nickelcene (C2H5)2Ni and ferrocene (C2N5)2Fe dissolved in 2-methoxyethanol. The alloy powder consisted of <10 nm and 70 to 80 nm particles. Thermodynamic analysis is shown to be a useful tool for gaining insight into the thermochemistry of the spray pyrolysis process.

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Abstract-Residual stresses in chemically vapor deposited monolithic and graded coatings in the Ti-C-N system were investigated as a function of substrate material and coating composition by X-ray diffraction Sin ' P method.The thermal expansion cgefficients (STE5) of the graphite substrates r3ng_~jd from 2.5~10 K to 8.6~10 K . TiEantum nitride (CTE 9.35~10 K ) and titanium carbide (CTE 7.5~10-K-) coasinq? deposited on the low-expansion substrates (CTEs 2.5-3.5~10 K ) exhibited crack networks which accounted for low stress levels measured in the coatings. A phenomenalogical explanation of the crack patterns was given. The coatings grown on the subsFraFes with high coefficients of thermal expansion (CTEs 7.8-8.6~10 K ) had no cracks. Residual stresses in the TiN coatings on these substrates were measured to be tensile. Whereas Tic coatings always exhibited compressive stresses ranging from -54f10 MPa to -288+18 MPa.The TiC,N, coatings deposited 03 she substrate with a thermal expansion coefficient of 8.6~10 K also had compressive stresses increased with increasing Tic mole fraction in the TiCxNy up to about 0.9 above which stresses decreased. The residual stresses in the top Tic layers of the graded TiN/TiC coatings with linear, parabolic and exponentional com os'tion profiles grown on the the same substrate (CTE 8.6x10-' K -' ) were measured to be compressive and about 475 MPa.Stresses in the coatings were calculated and attributed to the thermal expansion mismatch between the coating and the substrate. It was shown that the measured stresses were, in general, found to be in good agreement with the calculated ones.

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