针刺预制体分层对燃烧室C/C-SiC热防护结构的影响

Effects of delamination of needled preform on thermal insulation of C/C-SiC chamber

关键词:  针刺预制体分层  缠绕张力  燃烧室  热防护

Key words:  Delamination of needled preform  Winding tension  Combustion chamber  Thermal insulation

摘要:

开展了针刺预制体分层对吸气式发动机燃烧室C/C-SiC热防护性能影响的实验研究。分析了针刺预制体制作过程中出现预制体分层的原因,指出缠绕张力大小是导致制体分层的因素。通过比较有分层和无分层两种情况的实验结果,发现预制体局部存在的分层,造成了C/C-SiC热防护结构在热防护实验中出现结构破坏,说明由于预制体分层会引起C/C-SiC热防护结构存在局部层间结合力弱以及局部区域存在SiC基体聚集区,从而严重影响C/C-SiC热防护的结构完整性。为了避免出现针刺预制体分层,提出了在预制体制作过程中控制环向纤维缠绕张力的大小和均匀性,并在其完成初步致密化后进行CT检测,发现可能存在的分层,并指出预制体密度大小与预制体是否存在分层有一定的关联性,应通过实验结果和检测结果的统计分析,确定合理的预制体密度大小范围。提出从宏观上预制体密度指标作为评定预制体是否存在分层的判据。

Abstract:

Effects of delamination of needled preform on thermal insulation of C/C-SiC chamber in airbreathing engine have been investigated experimentally.The cause for delamination of needled preform was analyzed.The influence of the winding tension on the delamination of needled preform was studied.The results indicate that the delamination of needled preform can result in poor interlaminal bind force or local SiC aggregation layer and this can seriously affect the structural integrity of C/C-SiC thermal insulation when the chamber is under working conditions.In order to avoid the delamination of needled preform,the winding tension and uniformity during the needled preform production process should be controlled.Furthermore,CT technique should be adopt to detect whether there exists the delamination after needled preform is processed with CVD.Because of preform density related with delamination,the proper range of preform density should be found by statistical analysis for the results of experiment and detectmen.Then preform density can be used as a macro-evaluation criteria to detect whether there exists the delamination.