Alan Hase

Mechanism of surface magnetization by friction of ferromagnetic materials

Experiments showed that in the absence of an external magnetic field, the ferromagnetic materials Ni and Co undergo spontaneous magnetization of their frictional sliding surfaces as a result of tribological actions such as friction and wear. The magnetization phenomenon on the sliding surface was confirmed by measurements of the magnetic flux density and measurements of magnetic forces with a magnetic force microscopy. The mechanism of spontaneous magnetization by tribological action (tribomagnetization) is discussed in relation to the formation of elemental wear debris with a size of a few tens of nanometers, a size that is of the same order as that of a single magnetic domain particle, and of transfer particles that are formed by accumulation of debris adhering to the sliding surface in tribological processes.

Evaluation of Friction Phenomena of Brake Pads by Acoustic Emission Method

Brake pads are composite materials made from dozens of ingredients intended to simultaneously satisfy various performances such as brake effectiveness, wear and NV. For this reason, the friction phenomena that occur during braking are complicated. This also makes it difficult to clarify the relationship between the ingredients and brake performances. In the meantime, regulations on the use of raw materials (such as Cu) are being strengthened, because those materials exert bad influences on the environment and health. Therefore, the search for alternative materials is necessary. Given this information, it is important to clarify the friction phenomena, but that is not easy because the friction phenomena are complicated as mentioned above.

Structure and Electrochemical Properties of DLC/SiC Films on the Surface of Magnesium Alloy by Plasma Immersion Ion Deposition

DLC/SiC films (SiC as a transition layer) were prepared on the surface of magnesium alloy (AZ31) using a plasma immersion ion deposition (PIID) process. A dense and smooth DLC film can be observed by SEM. The surface hardness can be improved to 11.45GPa by deposition of the DLC film. Electrochemical tests show that the corrosion potential of AZ31 with DLC film is increased from -1.7V to -0.6V, which indicates that the DLC film improves the corrosion resistance of Mg alloy.