Abstract
The transverse-rupture strength of WC-10%Co alloy double coated with TiC and Al2O3 (total thickness, <14μm) by CVD process was mainly investigated in the temperature range from room temperature to 1273K. The results obtained were compared with those of the alloy singly coated with TiC.
The number density of cracks observed on the surface of coated layer after CVD was larger in double coated layer. The room temperature strength of double coated alloys decreased with increasing total thickness of layer and it was equal to that of singly coated alloys having the same thickness of layer. The strength of two sorts of coated alloys varied as a function of test temperature as follows: it dropped with increasing test temperatures up to about 873K; then increased at the higher temperatures in the range from 873 to 1173K; and dropped again above 1173K, showing the same strength as that of substrate at 1273K. The strength dependence of coated cemented carbides on test temperatures was in good contrast with that of substrate.
