Dry Friction Wear Research Articles

Wear Resistance of a Cr<SUB>3</SUB>C<SUB>2</SUB>-NiCr Detonation Spray Coating

Coatings can be applied to surfaces to improve the surface characteristics over those of the bulk properties and are widely used in tribological applications either to reduce wear and/or to modify friction during contact. One of the foremost coating methods for combating wear is thermal spraying. To prolong the life of steel slab continuous casting rolls, Cr3C2-NiCr detonation spray coating was processed on the roll surface in a steelmaking plant in China. This article studies the mechanical properties and wear resistance of this coating. The abrasive and dry frictional wear testing were performed using a pin-on-disk tester. Experimental results show that the wear resistance of the coated samples, i.e., coating reduces the risk of seizure compared to uncoated samples, is much better than those of the uncoated steel at room and elevated temperatures with any load and sliding velocity. The coating wear mechanisms under different test conditions are discussed.

Effect of Fe and Zr ion implantation and high-current electron irradiation treatment on chemical and mechanical properties of Ti–V–Al Alloy

Using Rutherford backscattering spectroscopy, nuclear elastic resonance analysis, atomic force microscopy, transmission electron microscopy, and wear resistance and microhardness tests, the alloy Ti41–V41–Al18 was investigated after Fe ion (60 kV) and Zr (40 kV) ion implantation and subsequent high-current electron beam (HCEB) irradiation at an energy flow density of 6 J/cm2, called duplex treatment. Profiles show that the maximum concentration of Fe ions was 16.5 at. % at 85 nm from sample surface and that of Zr ions was 0.85 at. % at 56 nm. The maximum of the Fe concentration profile was found to shift to the large sample depth toward after increasing the implantation dose. The surface alloy layer is composed of a number of structures: grains of dislocation substructure (2×1010 cm−2), grains with plates, and grains with packed martensite. The disorientation of regions is observed. After HCEB treatment, the disorientation of microregions increases (Δα=7.5°) and particles of Ti2Fe are formed. After double implantation, the dry friction wear and the friction coefficient decreased. After the duplex treatment, the thickness of the hardened layer and the wear resistance increased.

Brush plating: Recent property data

The information presented in this article provides quantitative property data on a variety of brush-plated deposits and shows that these coatings offer promise in applications involving wear and corrosion. CoMo, CoW, CoWP, NiCoZrO 2, and NiP improved wear resistance and service life of hot work dies. The CoWP alloy provided the best results. Trivalent Cr had a hardness similar to that of hexavalent tank-plated Cr and improved wear resistance in Taber tests. Cu was quite effective in preventing environmental embrittlement of iron aluminides. With 304 stainless steel, a sandwich coating of Cu and Ni inhibited stress corrosion cracking, thus indicating that this coating may be useful for field service protection against SCC and crevice corrosion at flange joints. NiCo deposits were worn to a much lesser extent than Ni or NiW in ball on disk tests. Hexavalent tank-plated Cr performed better than Ni and NiCo coatings in wear tests. Hard Ni, NiW, and CoW deposits were not deemed ready for replacement for tank-plated hexavalent Cr at Tinker Air Force Base. The tensile properties of a medium carbon steel were not markedly affected by plating with Ni, although there was some reduction in ductility; however, a marked reduction in fatigue strength was obtained. Shot peening, whether before or after brush plating, noticeably minimized the fatigue strength reduction. The weight loss in wear testing of a NiCoSiC deposit was only one third that of a Ni deposit. The SiC coating showed good results when used on ship engines. A NiFeWP deposit was noticeably more corrosion resistant in NaCl and H 2SO 4 than tank-plated Ni or hexavalent Cr. An alloy containing NiFeWS was superior to tank-plated hexavalent Cr under high load dry friction wear testing. NiP and NiCuP showed promising friction coefficients on 1045 steel. A PbSn alloy on 1017 steel noticeably reduced hydrogen permeation. An alloy containing PbSnNi exhibited a much lower friction coefficient and a better scuffing resistance than PbSn alloys.

Titanium- and Molybdenum-Boride Composite Coatings on Steels / Titanborid- und Molybdänborid-Verbundschichten auf Stählen

Two steels with 0.36 and 0.95 mass % carbon content are coated with Fe-Ti-B and Fe-Mo-B composite coatings by thermodiffusional metallization with Ti and Mo and subsequent boronizing. The coatings consist of a FeB surface layer and a Fe 2 B sublayer, both Ti- and Mo-alloyed. The dry friction wear resistance of the 0.36 % C steel is improved by these coatings by a factor of 3 to 4. In the 0.95 % C steel, the formation of TiC and Mo2C disturbs the continuity of the interface between the coating and the substrate and the dry friction wear resistance is practically not improved. The Ti-B layers are of greater wear resistance compared to the Mo-B layers.