TRIBOLOGICAL PROPERTIES OF B₄C-SiC-hBN COMPOSITE CERAMICS SLIDING AGAINST AISI 347 STEEL IMMERSED IN EMULSION

The powders of hBN, SiC, and B4C were employed as the raw ingredients to prepare the B4C-SiC-hBN composite ceramics by a vacuum high-pressure sintering method with hBN and SiC contents in the range of 0, 10, and 20 wt.%, respectively. A pin-on-disc testing equipment was used to assess the tribological properties of B4C-SiC-hBN composite ceramics with various hBN and SiC content when sliding against AISI 347 steel immersed in the emulsion. The experiment's findings indicate that the sliding COF of the B4C/AISI 347 steel pair marginally drops as the sliding distance increases. Besides, the sliding COF of the B4C-10 wt.% SiC-20 wt.% hBN/AISI 347 steel pair rapidly declines. By tribopairs of B4C-SiC-hBN composite ceramics against AISI 347 steel under the condition of lubrication by water-based emulsion, the steady-state friction may move into a state of mix lubrication as the hBN concentration rises, improving the tribological performance. The steady-state COF considerably decreases to 0.01 from 0.386 as the hBN and SiC concentration is increased to 20 wt.% and 10 wt.% from zero, showing a decreasing trend for both the B4C-SiC-hBN pin and AISI 347 steel disc samples' COWs. The steady-state friction of tribopairs of B4C-SiC-hBN composite ceramics against AISI 347 steel may enter a state of mixed lubrication in the emulsion. The wear resistance of composite ceramics was improved by the addition of hBN and SiC particles because of their lubricating and reinforcing effects. These findings offer valuable insights into the design and development of advanced composite ceramics for various industrial applications that require improved tribological properties.