Akira Ura

Influence of interposed wear particles on the wear and friction of silicon carbide in different dry atmospheres

Abstract The friction and wear characteristics of silicon carbide in sliding contact were studied in dry atmospheres of air, nitrogen, and argon. The rubbing surfaces and wear particles generated consisted mainly of silicon oxide in air, and retained their original composition of silicon carbide in the inert gases. Interposing wear particles reduced the wear and friction in air, and inversely increased the wear and friction in argon. This indicated that the wear and friction characteristics were improved by interposing wear particles softer and more brittle than the rubbing material itself. By producing a thin surface film composed of soft silicon oxide on hard silicon carbide before a run, the friction and wear characteristics in argon were markedly improved.

A Study of Friction due to Plowing on Deformable Materials.

Generally it is well known that a coefficient of friction in abrasive wear can be expressed theoretically as a summation of the two terms related with a plowing and an adhesive component. It is, however, necessary to correct each term in order to adjust them to actual phenomena. In this work the correction factors to obtain a plowing component and an adhesive component occupied in abrasive wear were experimentally evaluated using a cone with various angles. The test materials investigated are carbon steel as cone specimen and tin and alminium as flat specimen. As results they were much deviated from the calculated values theoretically and the values of the correction factors varied with experimental conditions.

Elastic Rotative Rigidity and Ultimate Resistance Moment of Uncovered Column Base in Posttension System with Cast Steel Base Plate.

A few tests and studies had been carried on in order to clarify the appraising method of elastic rotative rigidity and ultimate resistance moment of an uncovered column base in a posttension system with a cast steel base plate. The test method is to measure elastic rotative rigidity and ultimate resistance moment when the column, which is welded with a cast steel base plate connected with anchor bolts on a foundation of reinforced concrete and expanded mortar, is horizontally and axially loaded at the top. As a result, an appraising formula for elastic rotative rigidity and ultimate resistance moment of the column base in this system was derived.

Gas Flow in a Thin Annulus, With Application to a Stern Tube Seal

A newly-developed stern tube seal, which consists of two segmented carbon seals and two lip seals, has been evaluated. Fundamental air leakage tests under stationary conditions through very narrow clearances are presented. A theoretical analysis was carried out with cylindrical models in order to clarify the seal performance. The flow patterns were also visualized using simplified models. Analysis that included viscous friction, fluid inertia and losses at inlet and outlet under subsonic or choked flow was found to correlate well with the test results. Presented at the 45th Annual Meeting In Denver, Colorado May 7–10, 1990

Friction of Wire Rope in Cable Puller.

It is very important for a cable puller to grasp a wire rope tightly without any slippage and with no damage on both of the rope surface and cable gripper. The friction mechanism of a wire rope under a large deformation due to high grasp force, however, has not been sufficiently clarified. The present paper will report some results on friction of the wire rope under high compressive load on some cases such as under lubricated condition and under different contact conditions using three types of wire rope with steel core, fiber core and a galvanized rope with fiber core. As the results, the difference of contact area between the wire rope and gripper greatly affects the friction behavior; that is, the gripper with a curved surface can bring large friction force comparing with the gripper with a flat surface owing to its large real contact area, which is dominated by a restriction of the escape of wire between gripper surfaces and the deformation of a rope and a core.

Effect of deformation of the contact surface on wear and friction—a study on clarification of the mechanism of abrasive wear

Abstract The cutting action due to a protuberance between the rubbing surfaces in abrasive wear might be susceptible to adhesion at the rake surface in the direction of sliding. In the present paper we discuss an approach to clarify the abrasive wear mechanism, which is dominated by the effect of the difference in the contact deformation between both surfaces on wear and friction related with abrasive wear, on the basis of experiments conducted under ultrahigh vacuum. Although in practice it is generally very difficult to obtain a characteristic surface during sliding, we carried out experiments on surfaces that were as clean as possible to investigate the effect of the size of the deformed contact surface on the abrasive wear. Consequently, we were able to confirm that the friction differs according to which of the test pieces is the harder and, if the friction pair is composed of the same material, because the contact surface is deformed differently in each case.