CVD法による軟鋼板上へのZrB₂およびTiB₂-ZrB₂皮膜の生成

抄録

Chemical vapor deposition of ZrB₂ and TiB₂-ZrB₂ composites on mild steel substrates was carried out with the hydorgen reduction of ZrCl₄-BCl₃ and TiCl₄-ZrCl₄-BCl₃ mixtures.
The ZrB₂ deposition was carried out at substrate temperatures of 1273K and above, [ZrCl₄/ZrCl₄+BCl₃] gas ratios of 0.33 and above, and Cl/H ratios of 0.13 and below. The deposition of FeB was observed without these conditions.
TiB₂-ZrB₂ composite film was formed at 1273K, and its phase was determined by X-ray diffraction to be ZrB₂ within the range of film compositions equivalent to 0-77mol% TiB₂. TiB₂ phase was identified in compositions of 89mol% TiB₂ and above. The lattice constant of the composite film gradually decraesed with an increase in the titanium content of the film, and its sudden drop was observed at the boundary composition of TiB₂ and ZrB₂ phases.
A maximum micro-vickers hardness of about 4600kg·f/mm² was measured for composite films having the composition of TiB₂/ZrB₂=1 in molar ratio.