Tribological Properties of Magnet Structural Materials at Cryogenic Temperatures

在这个项目中，磁体结构材料的摩擦学性能在低温下进行了研究，因为摩擦加热由于滑动在磁体引起的淬火。（1）摩擦加热在液氦中的低温摩擦试验中，通过插入试样中的两个热电偶测量温升。对流加热表现为一个具有剧烈波动的脉冲。摩擦生热使温升增加，但两者之间不是线性关系。这意味着，由于液氦的冷却作用，产生的摩擦热并非全部，而是有一部分对试样的温升有贡献。模拟处理的是非稳态热传导反问题。从该模拟中，获得了试样的温度分布，其中温度随着深度从 ...更多信息 试样的界面。此外，积分热流表明，对温度上升的热量小于滑动过程中产生的摩擦热的50%。（2）低温真空中的摩擦试验超导磁体放置在真空容器中，因此，低温真空中会出现摩擦问题。搭建了该环境下的摩擦试验装置，对24种组合试件进行了摩擦试验。在诸如JN 2-JN 2的情况下，由于表面之间的粘附，摩擦系数在5 K下低，但在77 K下相当高。另一方面，在JN 2-CuNi的情况下，在4K下的摩擦系数高。这些性能取决于材料的硬度。硬度随着温度的降低而增加，并且在硬度的一定值以上防止粘附。硬度的温度依赖性也得到了，其中摩擦系数增加之间的20至50 K，并降低之间的80至110 K的JN 2-Cu。少

In this project tribological properties of magnet structural materials were investigated at cryogenic temperatures, because frictional heating due to sliding in a magnet caused the quench of it.(1)Frictional heatingIn the friction test at cryogenic temperature in liquid helium, temperature rise was measured by two thermocouples inserted into a specimen. Frictional heating appeared as a pulse with sharp fluctuation. Temperature rise was increased with frictional heat, but the relationship between them was not linear. This meant that not all the frictional heat generated but the some fraction of it contributed to the temperature rise of the specimen because of the cooling by liquid helium.Numerical simulation was carried out by using the experimental data of temperature rise. The simulation dealt with the inverse problem of unsteady heat conduction. From this simulation the temperature distribution of the specimen was obtained, where the temperature decreased steeply with depth from the … More interface of the specimen. Furthermore, the integrated heat flux showed the heat contributing to the temperature rise was less than 50 % of the frictional heat generated during sliding.(2)Friction test in vacuum at cryogenic temperatureA superconducting magnet is set in a vacuum vessel, and therefore, friction problem occurs in vacuum at cryogenic temperature. The experimental apparatus was constructed for the friction test in this environment, and friction tests were carried out for 24 combinations of specimen. In the cases such as JN2-JN2 the coefficient of friction was low at 5 K, but quite high at 77 K due to the adhesion between surfaces. On the other hand, in the case of JN2-CuNi the coefficient of friction was high at 4 K. These properties were dependent on hardness of materials. The hardness increased with decreasing temperature, and the adhesion was prevented above a certain value of the hardness. Temperature dependence of hardness was also obtained, where coefficient of friction increased between 20 to 50 K, and decreased between 80 to 110 K for JN2-Cu. Less