In this study, Na2SiO3, Na2MoO4, (NH2) NS and (NaPO3) 6 were selected as inhibitors to slow down the corrosion of gray iron in distilled water. Furthermore, the wear tests of Si3N4-gray iron pair lubricated with these inhibited solutions were carried out on a ring-block tester. The worn surfaces of specimens were observed under SEM and optical microscope. The components and structure of tribofilm formed on the worn surfaces of specimens were analyzed by XPS. The results indicate that the Na2SiO3 inhibitor can effectively prevent the gray iron from corrosion when its concentration in distilled water ranges between 0.01 and 0.1 mol/l. In the wear tests of Si3N4-gray iron pair under o.1 mol/l Na2SiO3 solution lubricated condition, the friction coefficient is as low as that of Si3N4-gray iron pair lubricated with distilled water. And the wear amounts of the Si3N4 and iron specimens are smaller than that lubricated with distilled water. The superior tribological characteristics are due to a tribochemical film formed on the wearing surfaces. The film consists of gel type amorphous SiO2 and silicates and makes the paired surfaces smooth.

Using distilled water and air lubricants, wear tests of ceramic-cast iron pairs were carried out on a M-200 type ring-block wear tester. For comparison, ceramic-carbon steel pairs were also tested under the same conditions. The worn surfaces of specimens were observed under scanning electron microscope (SEM) and optical microscope. Furthermore, the tribofilms were analyzed by using Augerelectron spectroscopy (AES), energy-dispersive X-ray spectroscopy (EDX) and image analysis technique. In the wear tests of Si3N4-cast iron pairs lubricated with distilled water, the friction coefficients of the pairs are just 0.02, and the wear rates of ceramic and iron are near zero. The superior triboiogical eharaeteristics are due to a tribochemical film. which is formed on the wearing surfaces and has sufficient thickness and area. However, in the test of a Si3N4-carbon steel pair lubricated with distilled water, the friction coefficient is still high because the tribochemicai film formed on the wearing surface is too thin and too small. A metal transfer film is formed on the ceramic surface when the ferrous metals slide against Al2O3. In this situation, the wear amount of Al2O3 is quite small, but the wear amount of the metals is large and the friction coefficient is rather high.

A tribofilm was formed during wear tests of a Si3N4-gray iron pair lubricated with distilled water. In order to clarify the formation process Of the film, wear tests of fhe Si3N4-gray iton pair with different sliding distances were carried out on a ring-block tester using distilled water as iubricant. After the tests, the worn surfaces of the gray iron specimens were examined under SEM. Furthermore, the components and the structure of the film were analyzed by AES, XPS, FTIR and XRD. Combining the obtained results, the following aspects are obtained. During the wear tests of a Si3N4-gray iron pair lubricated with distilled water, oxidation and hydrolysis of Si3N4 occur on the wearing surfaces, and the reaction product may be adsorbed by graphite flakes in the iron. As a result, a tribochemical film with a certain thickness and area, which consists of silicagel and graphite, is formed on the wearing surface. The film protects both Si3N4 and gray iron and makes the paired surfaces smooth. Therefore. the friction coefficient of the pair iS lowered down to as low as 0.002, and the total wear rates of Si3Na and Iron are near zero. However, because the products of oxidation and hydrolysis of Si3N4 cannot be accumulated on the wearing surface of carbon steel to form an eflfective tribofilm, both the friction coeffcient and the wear rate of the Si3N4-carbon steel pair lubricated with distilled water are high.

In order to overcome the shortcomings of present switch slide baseplates, a kind of epoxy composite was designed as lubricating coatings for switch slide baseplates. The wear tests of epoxy composite specimens paired with A36 steel specimens under air-lubricated condition were carried out on a ring–block wear tester typed M200. After the wear tests, the worn surfaces of steel specimens were examined by XPS and SEM. Furthermore, the wear reduction mechanism of graphite and MoS2 was discussed. The results showed that the graphite in epoxy composite can reduce the friction coefficient effectively, and increase the wear resistance of the epoxy composite greatly. MoS2 in epoxy composite is translated to MoO3 during the wear tests. Consequently, the friction coefficient of the pair cannot be decreased because MoO3 has not a layer structure. But MoS2 can effectively improve the wear resistance of the composite through restraining the epoxy transfer from the surface of composite to the surface of A36 steel.

The high temperature oxidation tests of Ni-Cr alloys which containing different alloying elements such as Mo, W, B, Cr and Ni were carried out through placing the specimen in a muffle for 100h at 800℃. In order to determine the effect of oxidation on the wear behavior of the alloys at elevated temperature, an interrupted oxidation-abrasion wear test was carried out on a high temperature three-body abrasive wear tester. Then the oxide and wear surfaces of the specimens were examined and the effect of the alloying elements on the oxidation and wear properties was discussed. Combining the obtained results, the following aspects are obtained. The high temperature oxidation stability of the carbide of the alloys can be improved by adding alloying elements Mo, Wand B. And the sufficient amount of alloying elements Cr and Ni in the alloys can raise the chemical stability of the matrix effectively. The controlling factors affecting the wear behavior are the oxidation stability of carbide and the oxidation synergistic performance of carbide with matrix. The excellent wear resistant performance of the carbide phase in alloy can be obtained only when the matrix phase support it effectively. Accordingly, the alloy still can't possess a good wear resistance when the oxidation synergistic performance of the carbide with matrix is poor, even the carbide oxidation stability is good.