The thermal properties of medium silicon - molybdenum vermicular iron are about three times of that of normal vermicular iron , so it is an ideal material for producing manifold 中硅钼蠕铁的抗热疲劳性能为普通蠕铁的3倍，因而是制造排气歧管的理想材料。
The second , chapter 4 assesses the effect of the content of tic on the thermal shock resistance of composites , and chapter 6 assesses the effect on the thermal fatigue resistance of composites 其次，第四章评价了tic含量对al _ 2o _ 3 - tic复合陶瓷抗热震性能的影响；而第六章评价了其对抗热疲劳性能的影响。
At first , by controlling the adding of al2o3 and tic starting powder size , chapter 3 assesses the effect of al2o3 and tic starting powder size on the thermal shock resistance of composites , and chapter 5 assesses the effect on the thermal fatigue resistance of composites 首先，本课题通过al _ 2o _ 3和tic起始粉末粒径的控制，在第三和第五章具体讨论了其对复合陶瓷抗热震和抗热疲劳性能的影响。
The thermal fatigue resistance of al2o3 - 20wt . % tic is the best , it is due to high kic and pore of the material . the pore decrease the stress extension of tip of cracks and delay themal shock fatigue cracks extension . 4 含20wt . tic的复合陶瓷具有高的k _ ( 1c )和较多的孔隙，这些空隙在热震疲劳时降低热震疲劳裂纹尖端的应力集中并阻碍裂纹扩展从而提高了材料的断裂抗力，故其具有最好的抗热疲劳性能。
For the manifold of sedan engine , the hest thermal fatigue properties can be obtained by keeping the percent of vermicular graphite at about 50 % , therefore it shouldn ' t he considered that the lowest e . g . percent limit of 50 % specified in chinese vermicular iron standard is too lower , and it is also not proper to take the v . g . percent as the basis for judging the level of production technology 摘要对轿车发动机排气歧管而言，蠕化率控制在50 %左右可以获得最佳的抗热疲劳性能，因此不能认为我国的蠕铁标准中规定的蠕化率高于50 %的要求偏低了，也不能把蠕化率的高低作为衡量工艺水平的依据。
