The possibility of using three kinds of new type composite materials as material for high speed sliding contacts was investigated. The results of this investigation were compared with the results of the low speed tests that were reported earlier. As a result of the above, it was discovered that for high speed rotation in the range from 0.014 m/s to 2 m/s, the order of merit did not significantly change. Based on this, it was concluded that if solid lubricant is effectively supplied to the sliding surface, the influence by frictional heat generated by high speed is slight. Of the three kinds of composite material, it was clarified that composite material (CMML-1) had the lowest contact resistance and Composite Material (CMML-3) had the lowest maximum frictional coefficient of friction. 'CM' and 'ML' are initialisms for 'Composite Material' and 'Material of Lubrication' respectively. The number that is attached to the material name is a numeric value that was set by this laboratory.

The author prepared new composition of Cu-Sn based composite materials containing lamellar solid lubricants, and measured their performance with focus on contact resistance and the coefficient of friction using a low-speed tribo-meter. Among three kinds of composite materials, the composite material containing 26wt.% of total solid lubricants was lower in both of contact resistance and the coefficient of friction and showed stable characteristics compared with those containing 25wt.% and 35wt.% respectively. The author analyzed the characteristics of these materials using several techniques including BSE image, element analysis through EPMA, and mapping analysis, and examined why the composite material containing 26wt.% of total solid lubricants showed higher performance.

Development of new sliding contact, usable under sever conditions such as high-temperature, extremely low-temperature or high vacuum, has recently become an urgent necessity. This research mainly examined the contact resistance and coefficient of friction of 3 kinds of self-lubricant composite materials with electrical conductivity and mechanical stiffness. The result showed that a composite material (CMML-1) containing the least quantity of solid lubricants [WS2, Gr.(Graphite)] among them was low in both contact resistance and coefficient of friction and less in fluctuation. By EPMA analysis, contribution of Sn to electrical conductivity was suggested.

In recent years, sliding electric contacts came to be often used under very severe conditions such as high temperature, extremely low temperature, high vacuum, etc. Conventionally, solid lubricants having excellent properties in lubricating performance are generally used compositely with a metal of high electric conductivity, because of their high electrical resistivity. In the present study, we proved that more excellent sliding electrical contacts can be produced with a design made by controlling the distribution on contact surface of a solid lubricant having excellent lubricating performance and of a metal with high electric conductivity through expansion of Greenwood's theory.

The lossy magnetic composite material made from soft magnetic metal powder and rubber is widely used as an EMI countermeasure material, due to its higher magnetic loss than those of spinel ferrites in microwave frequencies. In this paper, we clarify the material characteristics by measuring the relative complex permeability r and relative complex permittivity r of two kinds of composite materials in microwave frequencies. Since the composite materials are anisotropic, both r and r are measured as diagonal tensors by utilizing extended S-parameter method. The results show that the imaginary part of r of flaky-powder composite exceeded the Snoek's limit for the spinel ferrites which has been reported so far. The measured r and r are partially compared with those measured by cavity resonator method, and good agreement is obtained.

The constriction resistance of an electric contact has frequently been obtained using a model of only one circular contact spot of radius a. However, cases of a single contact spot are extremely rare as the interface of the electrical contact actually consists of numerous micro-contact spots. A contact is therefore regarded as the aggregate of several micro-contact spots, which are referred to collectively as a cluster. The constriction resistance of the cluster can be calculated as the sum of the self-resistance and mutual resistance of individual micro-contact spots. In the present study, this model is expanded slightly for practical application by normalizing a previous theoretical formula. In order to obtain the constriction resistance for contacts between composite materials and mating metals, EPMA analysis is applied so as to determine real micro-contact spots. Theoretical calculations of the constriction resistance of multiple contact spots is shown to be reasonably consistent with experimental results. In addition, the contact of a composite material and a mating metal is shown to be made up of multispots. The current was recognized experimentally to flow more easily at micro-contact spots in the cluster periphery. These experimental findings coincide with simulation results obtained by theoretical calculations.

This is an attempt to examine the contact resistance of a composite material which is used for sliding contacts. The composite material used here is sintered by dispersing the solid lubricant WS2 into the metallic base alloy Cu-Sn. A method based on Greenwood's formula is applied to determine how the calculated values are related to the contact resistance values obtained in our experiments. As a result, the composite material mated with the carbon specimen is found nearly to corresponds to the values of those calculated by the extended Greenwood's formula, whereas its value mated with the tungsten specimen does not. In short, it is concluded that the composite material mated with the carbon specimen consists of multispots.

Composite materials of solid lubricants, such as graphite, MoS2, WS2, etc., and metals are being used as the sliding electrical contacts. However, few reports have so far been presented on the detailed characteristics of such composite materials. It is shown in this report that contact resistance and coefficient of friction of the sliding contact of the composite material of Cu-Nb system against Cu were higher than those of the sliding contact of the composite material of Cu-Sn system against Cu. It was, further, found that composite materials of Cu-Sn system were superior to those of Cu-Nb system being both contact resistances and coefficients of friction lowered. At the same time, it was found that performances of composite materials of Cu-Sn alloy base containing exclusively WS2 were superior to those containing both WS2 and MoS2. It was, therefore, suggested that proper samples suitable for the service conditions should be selected from the composite materials of Cu-Sn system which contain exclusively WS2 for the practical applications.