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TRIBOLOGICAL PROPERTIES OF MAGNET STRUCTURAL MATERIALS AT CRYOGENIC TEMPERATURES IN VACUUM

真空低温下磁体结构材料的摩擦学特性

基本信息

批准号：
04650123
负责人：
IWABUCHI Akira
金额：
$ 1.28万
依托单位：
IWATE UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

项目摘要

In this project tribological properties of magnet structual materials were investigated at cryogenic temperatures in vacuum, because frictional heating in a magnet caused the quench of it, and frictional resistance determined the deflection of the structural components in vacuum.1. Frictional propertiesIn the friction test at cryogenic temperatures in vacuum, the temperature dependence of friction was examined from 4 K to 150 K for seven combinations of JN1-JN1, JN2-JN2, SUS316L-SUS316L, JN1-Cu, JN2-Cu, Cu-Cu and JN2-CuNi. There were three types of the frictional properties : (1) independent on temperature, where the friction was high at about 4.0 for Cu-Cu, JN2-CuNi, and SUSU316L-SUS316L, (2) gradual increase with temperature for JN1-JN1 and JN2-JN2, and (3) higher friction from 40 to 90 K for JN1-Cu and JN2-Cu. The composition of residual gases in a vacuum chamber was examined. H_2 gas at 20 K, N_2 gas at 50 K and CO_2 at 100 K appeared. The change in hardness of metals would determine the frictional properties.2. Temperature rise in vacuumTemperature rise due to frictional heating was tried to measure. However, the temperature of the moving specimen was not cooled enough, which resulted in the unsuccess of the measurement. The cooling was only the thermal conduction through the contact area between specimens. The new method to cool the moving specimen should be developed hereafter.3. Assessment of coated film in Nb_3Sn superconduction wireUsually Cr was plated on Nb_3Sn superconductiong wire to reduce AC loss. However, the coated film was separated by the small sliding, and Cu substrate appeared. The friction test and contacting resistance measurement were carried out in liquid helium for wires with different coating metals. Cr coated film was broken in the first 200 cycles, which was detected by the increase in coefficient of friction and the decrease in contacting resistance. Tungusten amorphous film with certain heat treatment showed the good performance.

本项目研究了真空低温下磁体结构材料的摩擦学性能，因为磁体中的摩擦热会导致其失超，而摩擦阻力决定了真空中结构部件的偏转。1.在真空低温摩擦试验中，考察了JN 1-JN 1、JN 2-JN 2、SUS 316L-SUS 316L、JN 1-Cu、JN 2-Cu、Cu-Cu和JN 2-CuNi七种合金组合在4 ~ 150 K温度范围内的摩擦系数。结果表明：（1）Cu-Cu、JN 2-CuNi和SUSU 316L-SUS 316L的摩擦系数在4.0左右，与温度无关;（2）JN 1-JN 1和JN 2-JN 2的摩擦系数随温度的升高而逐渐增大;对真空室中残余气体的组成进行了研究。20 K时出现H_2气体，50 K时出现N_2气体，100 K时出现CO_2气体。金属硬度的变化决定了摩擦性能.真空中的温升尝试测量摩擦生热引起的温升。然而，移动样品的温度没有被充分冷却，这导致测量不成功。冷却只是通过试件间接触区域的热传导。今后应发展新的运动试样冷却方法. Nb_3Sn超导线材镀层的评价通常在Nb_3Sn超导线材上镀Cr以降低交流损耗。然而，涂覆的膜被小的滑动分离，并且出现Cu基底。在液氦中对不同镀层金属的钢丝进行了摩擦试验和接触电阻测量。Cr涂层膜在前200个循环中破裂，这通过摩擦系数的增加和接触电阻的减小来检测。经过一定热处理的Tungusten非晶薄膜显示出良好的性能。