negative shrinkage 中文意思是什麼
negative shrinkage
解釋
負收縮-
The key to prediction of casting shrinkage / porosity lies in ascertaining the critical value of temperature gradient and niyama criterion. the thesis put forward two methods to ascertain the value, one is which is positive - direction and the other is negative - direction. we verify the realistic arithmetic of temperature gradient method and niyama criterion method by experiment, and we can draw a conclusion that the arithmetic is correct and reasonable in most cases and choice of developing tool is sound
臨界梯度值和新山判據臨界值的確定是實現縮孔縮松預測的關鍵，本文提出了確定臨界值的正向法和反向法，並以高鉻鑄鐵件縮孔縮松預測和鑄造工藝改進為研究對象，應用正向法，確定了溫度梯度法的臨界值為180 m 。 -
( 3 ) volume shrinkage of composite decreases greatly with wpu increasing, even can arrive a negative number, but thermal stability is still good. ( 4 ) toughening mechanism is that : the formation of high molecular linear amino formate construct is the toughening reason ; hydroxyl - terminated pu - prepolymer and pf react to produce chemical bond effect which participate cure ; carboxyl - terminated pu - prepolymer and pf form semi - ipn which make toughened pf occur maximum
（ 4 ）通過紅外光譜對pf / pu共混物分子結構進行的定性分析、以及掃描電鏡對沖擊斷面形貌進行的分析，可證明聚氨酯預聚物增韌酚醛樹脂的機理是：兩個體系都是由於高分子量的線形氨基甲酸酯結構而增韌；端羥基pu與pf在共固化中產生化學鍵效應，參與pf的固化；而端羧基pu則與pf形成半互穿網路而增韌。 -
Since pump high - flowability concrete commenced in late 70 ' s, it has been put to extensive application due to its advantages of fast, high - efficiency and stable quality. but its high flowing property and pumpability also cause some negative effects, such as serious shrinkage cracks at early age, which arouses wide social concern
泵送高流態混凝土自從70年代末期產生以來，以其快速高效、質量穩定等特點得到了廣泛的應用，但它的高流動性和可泵性也產生了一些負面作用，如早期收縮開裂現象比較嚴重，引起了社會的普遍關注。
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