问题 问答题 简答题

用于防腐蚀工程的玻璃纤维毡,主要有哪两种形式?其基本特点有哪些?

答案

参考答案:

用于防腐蚀工程的玻璃纤维毡,主要有短切毡和表面毡。

其基本特点为:短切毡由长度50~70mm不规则分布的短切纤维粘结而成。胶粘剂常用不饱和聚脂、乙烯基酯树脂,也有用机缝的方法使其具有一定强度。它铺覆性好,无定向性,价格便宜,所以用途很广,不仅适用于手糊成型,也可用于模压及各种连续预浸渍工艺。

表面毡用胶粘剂将长玻璃纤维随机、均匀铺放后粘结成毡,这种毡很薄,约为0.3~0.4mm,主要用于手糊成型制品表面,使制品表面光滑,而日树脂含量较高,防止胶衣层产生微细裂纹,有助于遮住下面的玻璃纤维纹路,同时还使表面具有一定弹性,提高其抗冲击性、耐磨性、耐老化性、耐腐蚀性。

单项选择题
单项选择题

Watch a baby between six and nine months old, and you will observe the basic concepts of geometry being learned. Once the baby has mastered the idea that space is three-dimensional, it reached out and begins grasping various kinds of objects. It is then, from perhaps nine to fifteen months, that the concepts of sets and numbers are formed. So far, so good. But now an ominous development takes place. The nerve fibers in the brain insulate themselves in such a way that the baby begins to hear sounds very precisely. Soon it picks up language, and it is then brought into direct communication with adults. From this point on, it is usually downhill all the way for mathematics, because the child now becomes exposed to all the nonsense words and beliefs of the community into which it has been so unfortunate as to have been born. Nature having done very well by the child to this point, having permitted it the luxury of thinking for itself for eighteen months, now abandons it to the arbitrary conventions and beliefs of society. But at least the child knows something of geometry and numbers, and it will always retain some memory of the early happy days, no matter what vicissitudes it may suffer later on. The main reservoir of mathematical talent in any society is thus possessed by children who are about two years old, children who have just learned to speak fluently.

The author’s attitude toward early childhood education can best be described as a sort of ().

A. indifference

B. suspicious

C. compromising

D. surprising