M. Nunogaki et al., Preparation of thick functionally graded layers of ceramics by surface modification of tantalum and titanium using high temperature plasma processing, MATER TRANS, 42(3), 2001, pp. 457-459
Surfaces of metals, such as Ta acid Ti, have been changed successfully to a
new type of ceramic layers having the compositional gradient by means of t
he plasma processing at high temperature above 900 degreesC. Surfacer of Ta
and Ti were transformed to thick layers of ceramics, i.e. TiC, TiN, TaC or
TaN components, respectively, by carburizing or nitriding. Resultantly, a
Vicker's hardness of each modified sample surface remarkably increased over
3000 kg/mm(2) The density of carbides or nitrides in the modified layer an
d at the interface was measured to decrease with depth. The width of interf
ace was wide about 7 mum, in the case of TiC. Additionally, the irradiation
of 20 MeV-electron beam to samples as the pretreatment before the plasma p
rocessing was effective to increase the thickness of modified layer.