SiCf/Al复合材料的界面性能及机制

通过对SiC纤维表面富C，富SiO2和双涂层处理的SiCf/Al复合材料试样的不同热压制备工艺研究，发现热压温度和压力均对纤维表面改性后的界面性能有相当大的影响，温度和压力的提高改善了富SiO2处理试样的界面性能，却使富C和双涂层处理试样的界面性能蜕化，研究了产生这种影响的机制。     

Effect of Heat Treatment on Acoustic Emission in 7075-T651 Aluminum Alloy

The longitudinal(L),long-transverse(T)and short-transverse(S)orientated samplesof precipitation-strengthened 7075-T651 aluminumalloy were examined.The acoustic emission(AE)characteristicsmeasured during tensile deformation in the alloywere related to prior aging treatment and orienta-tions of samples.A rms AE peak occurred in all the samplesat plastic strain greater than one percent.The heights of peaks have been measured as afunction of prior heat treatment.The shiftof the peak location was dependent on heat treat-ment in samples with L- and T-orientation.The pre-yield,burst-type emission(PYBE)wereobserved in S-orientated samples.The behavioursof PYBE were as a function of prior ageing treat-ment too.The stress and plastic strains at whichthe AE peak stress were generated were consistentwith the peaks arising from the fracture anddebonding of inclusions.Waveform frequencyanalysis of AE signals and fractographic observa-tions using SEM as well as data of microhardnessand charpy test were also consistent with be-haviours of AE,that is,high stress requiredfor the rms peak or the initiation of the PYBE,was higher for the heat treatment,at whichthe interface between inclusion and matrix wasweaker.     

腐蚀疲劳过程的声发射

利用声发射技术研究了SM50B-Zc低强结构钢在淬火及正火两种状态下在空气和流动的3.5％NaCl水溶液中的疲劳过程。试验结果表明:在声发射振铃计数率与疲劳裂纹扩展速率及应力强度因子范围之间有良好的对应关系。     

钢丝绳疲劳损伤声发射测试

对疲劳条件下6×19S FC钢丝绳进行了声发射(AE)测试,结果表明,用AE事件的幅值、持续时间、能量和计数参数可综合表征断丝事件;在钢丝绳失效之前的60％处即能给出失效的AE预警;适当提取钢丝裂纹开裂的AE事件有利于表征钢丝绳的总体损伤情况。