(State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China)
Keywords:
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CLC:
PACS:
TB332
DOI:
10.7502/j.issn.1674-3962.2013.11.04
DocumentCode:
Abstract:
To improve the ablation resistance，ZrB2-SiC coatings were prepared by two-step slurry painting on C/C composites. The ZrB2-SiC-ZrC transition layer was prepared by reactive sintering,then ZrB2-20%SiC-5%Si3N4、ZrB2-15%SiC-20%MoSi2、ZrB2-15%SiC-20%TaC outer coating were prepared on it.The ablation test was conducted under oxy-acetylene torch at 2500℃ for 60s. X-ray diffractometry and scan electron microscopy were employed to investigate the microstructure and ablation mechanism.The results show that the transition layer had a good combination with the matrix,and no obvious lamination appeared when connected to the outer layer.Owing to the effect of Si3N4 and MoSi2 as sintering aids,the structure of ZrB2-20%SiC-5%Si3N4 and ZrB2-15%SiC-20%MoSi2 outer coating were quite dense.Coating ZSS and ZSM showed better ablation resistance.The linear ablative rate and mass ablative rate of coating ZSS and ZSM were 0.075mm/s, 0.0081g/s and 0.018mm/s,0.0064g/s respectively.The coating ZST did not show effective oxidation protection because of its loose structure,and it caused the burning through of the coating