Ablation mechanism of AlSi/graphite dissipative heat protective composites under an oxy-acetylene torch

To improve the ablation resistance of graphite, AlSi alloy was used as a dissipative agent to fill the pores of graphite matrix by pressure infiltration method to prepare AlSi/graphite composites. The microstructure evolution and ablation behavior of the obtained AlSi/graphite composites were investigated under oxy-acetylene flame after ablating for varying lengths of time. Subsequently, the effect of heat dissipation through the AlSi alloy was quantitatively analyzed by data processing technique. Experimental results showed that the AlSi alloy reduced the surface temperature by about 300 °C in the first 20 s, and the linear ablation rate of the AlSi/graphite composite is found to be 119.3% lower than that of the graphite itself ablated for 10 s. The strengthening of ablation resistance is mainly achieved by heat dissipation and oxygen dissipation. However, it gradually decreases with continuous consumption of the AlSi alloy during ablation. Among these, the contribution of heat dissipation to the ablation resistance gradually increased from 10.1% at 10 s to 62.1% at 60 s.