应力集中在很大程度上提高了(),降低了金属的塑性。
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Prolonged contact between all irreversible hydrocolloid impression material and gypsum should be avoided because()
A. the gypsum will show large cracks
B. a soft,chalky surface call form. on the gypsum
C. discoloration ofthe gypmlm will occur
D. the inclusion ofpowder in a hydrocolloid impression material
Alginate impressions should be poured()
A. Within 10 minutes
B. Within 1 hour
C. Within 24 hours
D. As soon as possible
加成型硅橡胶印模材料制造商特别指出,应取印模后1小时才能灌制高强度人造石模型。环氧树脂模型比较理想,因此灌制被推迟1小时。在分离时,模型上有小凹陷。造成这一问题的原因是什么?如何避免?
冷轧厂1780机组酸轧线成品厚度范围(),宽度范围()。