Preparation of CVD diamond coatings on gamma titanium aluminide using MPECVD with various interlayers

摘要

CVD diamond coatings were deposited on to gamma-TiAl surfaces using a microwave plasma enhanced CVD to improve wear properties and the performance of gamma-TiAl Diamond coatings were directly deposited on to gamma-TiAl substrates and deposited on to TiC, Ti5Si3, Al2O3 + TiO2, and Si interlayers prepared on gamma-TiAl substrates. The diamond coatings deposited directly on gamma-TiAl suffered severe delamination and cracked. Those deposited on TiC and Ti5Si3 interlayers partially delaminated, whereas those deposited on Al2O3 + TiO2 and Si interlayers adhered well to the underlying Surfaces. The diamond films obtained were characterized using scanning electron microscopy, Raman spectroscopy, and X-ray diffraction. Raman spectra showed that polycrystalline and nanocrystalline diamond films grew on gamma-TiAl. Residual internal stresses of the diamond coatings deposited on interlayered-gamma-TiAl were estimated experimentally from Raman spectra. The coatings prepared on Al2O3 + TiO2/gamma-TiAl and Si/gamma-TiAl showed lower residual stresses. (c) 2008 Elsevier Ltd. All rights reserved.