Ablation resistance property of nitride filled polytetrafluoroethylene composites based on CO₂ continuous laser simulation

In order to improve the arc-resistance ablation property of polytetrafluoroethylene (PTFE) nozzle composites of high voltage circuit breaker, micro or nano size boron nitride (BN) or aluminium nitride (AlN) with different ratios were dispersed into PFTE matrix. CO₂ continuous laser was used for ablating PTFE nozzle material to simulate electric arc ablation process. The effects of light reflectance, thermal conductivity and relative dielectric constants on ablation amount were analyzed. By comparing ablation amount of composites and numerical analytical results, the key factors affecting ablation amount are thermal parameters of materials (thermal conductivity and thermal diffusion coefficient). BN/PTFE composites have higher ablation resistance property compared with AlN/PTFE composites. The thermal conductivity of 10.0% BN/PTFE composites is up to 0.46 W/(m·K) which is 92% higher than that of pure PTFE. The mass loss of 10.0% BN/PTFE composits in ablation process is 21.8 mg, which is 47% less than that of 3.0% AlN/PTFE composites. The ablation resistance property of nozzle composites is effectively improved.