Yuh-Ping Chang

An Experimental Study on Heat Conduction and Thermal Contact Resistance for the AlN Flake

The electrical technology has been a fast development over the past decades. Moreover, the tendency of microelements and dense division multiplex is significantly for the electrical industries. Therefore, the high thermal conductible and electrical insulating device will be popular and important. It is well known that AlN still maintains stablility in the high temperature. This is quite attractive for the research and development department. Moreover, the thermal conduct coefficient of AlN is several times larger than the others. Therefore, it has been thought to play an important role for the radiator of heat source in the future. Therefore, this paper is focused on the studies of heat conduction and thermal contact resistance between the AlN flake and the copper specimens. The heating temperatures and the contact pressures were selected as the experimental parameters. According to the experimental results, the materials are soft and the real contact areas between the interfaces significantly increase under higher temperatures. As a result, the thermal contact resistance significantly decreases and the heat transfer rate increases with increasing the heating temperature or the contact pressures.

The Variations of Thermal Contact Resistance and Heat Transfer Rate of the AlN Film Compositing with PCM

The electrical industries have been fast developing over the past decades. Moreover, the trend of microelements and packed division multiplex is obviously for the electrical industry. Hence, the high heat dissipative and the electrical insulating device have been popular and necessary. The thermal conduct coefficient of aluminum nitride (i.e., AlN) is many times larger than the other materials. Moreover, the green technology of composite with phase change materials (i.e., PCMs) is worked as a constant temperature cooler. Therefore, PCMs have been used frequently for saving energy and the green environment. Based on the above statements, it does show great potential in heat dissipative for the AlN film compositing with PCM. Therefore, this paper is focused on the research of thermal contact resistance and heat transfer between the AlN/PCM pairs. According to the experimental results, the heat transfer decreases and the thermal contact resistance increases under the melting process of PCM. However, the suitable parameters such as contact pressures can be used to improve the above defects.

A study on the properties of heat conduction and tribology for the pair of copper and AlN film with phase change materials

It is well known that AlN still maintains stable in the high temperature conditions. This is quite attracted for the electrical engineering. Moreover, the heat conduction of AlN is several times efficacious than the other ceramics. Hence, it is widely used for the heat dissipation. The green technology of composite with PCM is always worked as a constant temperature cooler. Therefore, PCM has been thought to show great potential for saving energy and green environment. As a result, it is worth investigating in heat dissipative for the pair of copper and AlN film with PCM. However, the properties of this material pair will be quite complex. It is necessary to further theoretical analyze and experimental clarify for the reliability and the feasibility. Therefore, the thermal contact resistance of copper and AlN film with PCM were dynamic measured in this paper to investigate the heat conduction of the pair. Besides, the continuous variations of electrical contact resistance and friction coefficient were synchronous measured to study the tribological properties of the pair.

Effects of Doping Elements on the Friction and Wear of SUJ2 Steel Sliding against Aluminum Alloys

Damage to mechanical components caused by wear is considered to be an important issue for mechanical engineers. For the purpose of wear resistance, it is necessary to improve the material properties of the mechanical elements. Furthermore, low friction plays an important role in saving energy. Hence, it is important to establish a key technology for wear resistance and low friction through appropriate materials science for related industries. In general, the tribological properties of aluminum alloys are very different from those of steels. Hence, aluminum alloys should be specially considered and clarified for their tribological properties before being applied industrially. This paper therefore aims to further investigate the effects of the content of doping elements on the friction and wear of the selected aluminum alloys. From the experimental results, it can be concluded that the higher the Si content, the smaller the friction coefficient, and the milder the variation. The higher the content of iron and copper, the more materials are removed, showing better machinability. Moreover, three frictional models and wear mechanisms that describe the effects of the content of doping elements on the friction and wear are proposed. The wear mechanisms change as the silicon content increases, from the junction growth to the wedge and the ploughing particles. As a result, better choices of aluminum alloys with regards to friction and wear can then be made. These results have great practical importance.

Surface voltages of tribo-electrification during dry friction process for the typical four polymer pairs

The surface voltages of tribo-electrification for the typical four polymer pairs of POM/POM, POM/PE, POM/PA, and POM/PP were investigated in this study. The vertical rotation friction tester was used to conduct the experiment in the dry and severe wear condition. By the experimental results, the relationships between frictional characteristics and trib-electrification are clarified. Moreover, the experimental results seem that the surface voltages of tribo-electrification for the typical four polymer pairs are determinant by oxide atom of the chemical bonding.

Tribological properties of SUJ2 steel sliding against Al-Si alloys: Role of content of silicon

The wreckage of mechanical elements caused by the wear has been thought as an important problem for the mechanical engineers. Hence, it is necessary to improve the material properties of mechanical elements for the purpose of wear resistance. Moreover, low friction always plays an important role for saving energy. The technologies of materials science and surface engineering have been used widely for these purposes in the industry. Therefore, it is very important to further establish the key technology of wear resistance and low friction by proper materials science for the related corporation. It is well known that the tribological properties of aluminum alloys are much different from the steels. Therefore, it should be special considered and clarified for the aluminum alloys before the industrial applications. This paper is based on the above statements to further investigate the effect of content of silicon on friction and wear of the five aluminum alloys. To monitor the tribological behaviors between the frictional interfaces, the variations of friction coefficient were dynamic recorded during the friction processes. Wear loss was measured by an accuracy balance and SEM was used to observe the wear particles after each friction test. As a result, the better quality of wear resistance and low friction of the aluminum alloy can then be obtained for the industry.

A Method of Using Continuous Surface Magnetization and Friction Coefficient Variations for Monitoring the Tribological Properties of CrO2/SS400 Steel for the Flexible Gas Seal

Abstract The experimental results demonstrate that the dynamic variations in surface magnetization and friction coefficient showed great potential for determining the onset of CrO2 film fracture. It is also shown that the CrO2 film resulted in low friction and low surface magnetization during the friction process, and is wear-resistant. Therefore, this study is novel and practical for the industry. Graphical Abstract CrO2/SS400 sample demonstrates no rutting wear, high wear resistance, low friction coefficient, and low magnetization.

Effects of oxygen and nitrogen gases on the dynamics between the interfaces of self-mated titanium pairs

The chemical reactions of titanium in air include both TiO2 and TiN. The phenomena are quite complex, and the reaction mechanisms are still unclear. However, as titanium is in widespread use all over the world, it is important that the reaction mechanisms be thoroughly investigated. Therefore, in this study, the continuous variations in the electrical contact resistance and the friction coefficient are simultaneously measured to monitor the dynamics of self-mated titanium pairs in an air, O2 or N2 gas flow. When a large amount of TiO2 formed on the surface of the plate for Ti/Ti, the results showed the tribo-physical phenomena of higher electrical contact resistance, friction coefficient almost doubled and severe wear. When a large amount of TiN formed on the surface of the plate for Ti/Ti, the results showed the tribo-physical phenomena of lower electrical contact resistance, friction coefficient almost halved and mild wear with some lubrication. Therefore, variations in the electrical contact resistance can be applied to determine whether the chemical reaction on the surface was TiO2 or Ti with TiN. The unsymmetrical frictional models and wear mechanisms of the self-mated titanium pairs in the air, O2 or N2 gas flow were proposed.

Effects of Nitride on the Tribological Properties of the Low Carbon Alloy Steel

The technology of composite heat treatment is used popularly for low friction and wear resistance of drive elements. A large number of papers about the heat treatment technology had been proposed. Especially, the nitride treatment has been used widely for the purpose of wear resistance and low friction in the industry. Therefore, the self-developed vertical ball/disk friction tester with the measurement system was used to study the effects of nitride on the tribological properties of the low carbon alloy steel—SCM415— in this study. The experiments were conducted under dry and severe wear conditions. The variations of friction coefficient and surface magnetization were simultaneously recorded during dynamic friction process. After each test, the microstructures of the wear particles were observed and analyzed under a SEM, and the depth of wear track is measured by means of a surface tester. According to the experimental results, the wear resistance of the specimens with carburizing-nitride is significantly larger than the case of nitride-carburizing. Moreover, the surface magnetization was especially larger for the case of nitride-carburizing. As a result, the wear particles always stay in the interfaces and the wear mechanism becomes complex. Therefore, it is necessary to put nitride after carburizing for the composite heat treatments.

The sensitivity of using tribo-electrification responses for monitoring the tribological properties between a thin film of tin

The traditional method of using the continuous variation of the friction coefficient with sliding distance to monitor the tribological properties between the contacts of soft metal films is generally low in sensitivity. This paper proposed the novel method of using instead the continuous variation of tribo-electrification voltage. This method was investigated experimentally for the dry friction sliding of iron on copper coated with a thin film of tin and was shown to be much superior to the traditional method in terms of sensitivity. The method has the added advantage of the ability to assess the solid to film lubrication of the soft metal film. Finally, a continuous model to represent the wear mechanisms for iron sliding against copper coated with a thin film of tin was proposed.