Understanding the Impacts of Adhesive on the Tribological Performance and High-Temperature Oxidation Behavior of Glass Lubricant Coatings in Hot Extrusion Process of Titanium Alloy

The high-temperature tribological performances of glass lubricant coatings with different weight ratios of the adhesive of Al(H2PO4)3 and glass powder were investigated. The experimental results revealed that the average coefficient of friction (COF) and wear rate were presented a changing trend of first increases and then decreases with increasing weight ratios of Al(H2PO4)3. The minimum value of the average COF (0.09) and wear rate (2.2 x 10-5 mm3/N<middle dot>m) were obtained when the weight ratio of Al(H2PO4)3 and glass powder was 3:2. The oxidation tests were carried out to evaluate the oxidation resistance of glass lubricant coatings. The mass gains of the Ti6Al4V alloy plate with glass lubricant coating were 0.22 mg/cm2, 0.33 mg/cm2, and 1.2 mg/cm2 at the oxidation temperature of 800 degrees C, 900 degrees C, and 1000 degrees C, respectively. The values of the mass gains were decreased by 73.8%, 91.0%, and 84.8%, compared with the uncoated Ti6Al4V alloy plate, respectively. The results demonstrated that the glass lubricant coating shows excellent oxidation resistance. In addition, based on the experimental analysis and characterizations of the coatings, the friction-reduction and anti-wear mechanisms were proposed. The excellent friction reduction and anti-wear performance can be attributed to the protective effect of lubricant coating, and the production of the lubrication layer of Si/Al, Si, P/Al, and P on the worn surface.