Structural design and wear properties of TIG arc brazing tin-based babbit to mild steel

The tin-based babbit with different layer thickness was bonded to mild steel via TIG arc brazing. The microstructure, microhardness, wear properties and phase formation mechanism near the interface of the arc brazed layer were investigated by the optical microscope (OM), X-ray diffraction (XRD), high temperature friction and wear testing machine (HTFWT), laser scanning confocal microscope (LSCM), electron microscope (SEM) and energy dispersion spectrum (EDS). It can be found that in the arc brazing seam region, the thinner layer made it possible to form larger size SbSn monotectic phase that connected together and some Fe-Sn IMCs were formed near the interface. So that when the layer thickness was 0.5 mm, the microhardness of arc brazing tin-based babbit layer was the largest and the antifriction property was the best. Moreover, on the brazing tin-based babbit interface, Fe elements were transited and diffused from mild steel into the brazing seam region. Element concentration of Fe was high near the steel interface and formed concentration gradient in the liquid metal layer, which was helpful to promote the metallurgical reaction. Phase constituents of the brazed joint interface were Fe, Fe3Sn, FeSn and FeSn2, formed in the metallurgy of Fe from mild steel and the Sn from tin-based babbit.

Research on Graphene Preparation by Liquid Phase Ultrasonic Exfoliation and Antifriction Performance in Water

The different layers of graphene were prepared by liquid ultrasonic direct exfoliation. The dispersion stability of graphene in water under different ultrasonic time, the antifriction Performance, and the elements and morphology of the wear surface are investigated. The wear mechanism of graphene solution was preliminarily discussed. The results indicate that graphene with thickness of 10nm-150nm can be produced by ultrasonic peeling expanded graphite and the dispersion stability of graphene aqueous is best when sonicating for 3h. The antifriction property and wear mechanism of graphene aqueous vary with the graphene content. When graphene content is 0.01wt%, the antifriction performance of graphene aqueous was optimum and its wear mechanism was abrasive wear.

The Influences of the Plating’s Hardness, Abrasion and Antifriction Property Caused by the Adding of Nano- Al2O3 and PTFE

Composite plating Ni-P-PTFE- nano- Al2O3was made by adding nano-scaled Al2O3and PTFE into chemical plating Ni-P alloy plating solution. The influences of the plating material’s hardness, abrasion and antifriction property caused by the additive amount of nano- Al2O3and PTFE were studied in the paper. The results indicate that the composite plating’s hardness, wear resistance and antifriction can be greatly improved by adding nano- Al2O3and PTFE into it.

ANTIFRICTION PROPERTY OF MICROARC OXIDATION COATING ON TITANIUM ALLOY UNDER SOLID LUBRICATING SLIDING CONDITION

Ceramic coatings were fabricated on Ti6Al4V alloy surface by microarc oxidation (MAO) in Na 2 SiO 3–( NaPO 3)6– NaAlO 2 solution using an AC power supply. Microstructure and phase composition of coating were characterized by SEM and XRD, respectively. The antifriction property of the coating with and without solid lubricant sliding against SAE 52100 steel ball was investigated on a pin-on-disk friction and wear tester. The results show that the microarc oxidation coating is relatively dense and uniform, mainly composed of rutile and anatase. The coating sliding against the steel has friction coefficient as low as 0.2–0.3 at an applied load of 0.5 N and sliding cycle below 2500, which is much smaller than that of uncoated Ti6Al4V against the same counterpart. The transferring of materials from the softer steel ball onto the coating surface is the main wear event, while the microarc oxidation coating is characterized by slight abrasive wear and adhesive wear. Introducing solid graphite lubricant into the porous surface of microarc oxidation coating significantly improves the long-term antifriction property (registering friction efficient of 0.15 in the long-term sliding) under a similar sliding condition. This improvement is attributed to the reduction of materials that are transferred from the softer steel ball onto the coating surface.