| Popis: |
23% of worlds total energy consumption is lost due to friction and wear. Liquid lubricant or grease are commonly used to reduce friction. However, they do not work in vacuum or space (will vaporize), in food & medicine production industry, artificial human joints (will contaminate) etc. In such cases, solid lubricants can be the only option. Polytetrafluoroethylene (PTFE) is commonly used as a solid lubricant due to its ultralow friction coefficient (µ=0.04~0.20). However, its high wear rate (K~10 -4 mm 3 /Nm) motivated researchers to study its composites for a reduced wear rate. While most fillers could reduce its wear rate by up to 1000 times, certain α-alumina was found to be producing ~10,000 times lower wear rate. Tribofilm generation and tribochemistry were found to be the cause of this ultralow wear behavior. However, while reducing the wear rate of PTFE, α-alumina can increase its friction coefficient about 2 times. This study strived to find a filler that can produce similar or better wear reduction effects while retaining the low wear rates of unfilled PTFE. The study revealed the friction coefficient of PTFE-Cr against brass 260 countersample to be around half that of ultralow wear PTFE α-alumina’s (µ=0.12 vs µ=0.2~0.25) with 30 times lower wear rates of PTFE α-alumina’s (~50,000 times lower than unfilled PTFE). PTFE-Ti and PTFE-Mn on brass have also shown to perform better than PTFE-α-alumina both in reducing wear rates and friction coefficient. |
