聚甲醛塑料,俗称赛钢,为结晶性热可塑性塑料,具明显熔点165~175℃,性质Zui接近金属。
优点 1、具高机械强度和刚性
2、Zui高的疲劳强度
3、环境抵抗性、耐有机溶剂性佳
4、耐反覆冲击性强
5、广泛的使用温度范围(-40℃~120℃)
6、良好的电气性质
7、复原性良好
8、具自已润滑性、耐磨性良好
9、尺寸安定性优
缺点 1、加工过程若长时间高温下易起热分解
2、无自熄性
3、抗酸性差
4、成形收缩率大
用途 电子电器:洗衣机、果汁机零件、定时器组件
汽 车: 车把零件、电动窗零件
工业零件:机械零件、齿轮、把手、玩具、螺杆
At the mention of the heroic John bethought himself of Haydon,and suggested his name; hence his visit to London, and his proposedinterview with Haydon. The two brothers went together to callupon the “painter of the heroic” at his studio in ConnaughtTerrace, Hyde Park. There was some difficulty about theiradmission, and it turned out afterwards that Haydon thought theymight be duns, as he was very hard up at the time. Hiseyes glistened40 at the mention of the £100. “I amnot very fond of painting portraits,” he said, “but a mayor is amayor, and there is something grand in that idea of the Normanarch.” And thus Mayor Hawkes came to be painted by BenjaminHaydon, and his portrait may be found, notwithout diligent41 search, among the many municipalworthies that figure on the walls of thatmost picturesque42 old Hall in Norwich. Here isBorrow’s description of the painting: