Papers by Keyword: Friction Modifier

Abstract: Lignite bottom ash is an industrial byproduct from the combustion of lignite coal in electric power plants. The ash is composed of various hard metal oxides, and therefore may be suitable for use as a low cost friction modifier in friction materials. This research studied the effect of lignite bottom ash additions (up to 20 weight percent) on the tribological properties of a graphite-steel composite (5 weight percent graphite and 95 weight percent high carbon steel). The powder compositions were uniaxially pressed with 300 MPa applied pressure to produce disc shaped samples. The samples were sintered at 1,100 °C for 30 minutes in a reducing atmosphere of 90 percent nitrogen and 10 percent hydrogen. The friction coefficients were measured using a ball-on-disc tribometer. It was found that the addition of bottom ash increased the friction coefficients of the samples due to the increased abrasiveness provided by the bottom ash. The density of the samples was reduced due to the lower theoretical density of the bottom ash compared to the steel that it replaced. The hardness of the samples were found to be independent of the amount of lignite bottom ash, possibly as a result of a hard particle reinforcement effect.

Abstract: The aim of this study was to determine the influence of powder fillers on the tribological properties of composite materials used for dental fillings. The investigated composites contain a fluoridated filler (based on Ba-Sr-Al-P-Na-silicate glass fillers) as a fluoride source as well as different powder fillers (friction modifiers) e.g. silicon nitride (Si3N4), boron nitride (BN), polyethylene (PE), polytetrafluoroethylene (PTFE). Composite disks were photo-cured and tested for wear against harder stainless-steel counterface. Wear tests were carried out by means of special tribotester in the presence of phosphate buffer as a lubricant. Influence of the load and filler contents on the friction coefficients and wear were estimated. The interaction between the filler particles and organic matrix and its influence on the tribological behavior of prepared specimens were observed. Organic powder fillers (PE, PTFE) reduced the friction coefficient and the wear of tested composite materials for dental fillings. Inorganic friction modifiers (Si3N4, BN) did not exhibit this effect.

Abstract: This paper presents an experimental investigation of the influence of scuffing conditions on two-roller test rig. The prediction of Scuffing load capability model for the gear oils containing molybdenum dithiocarbomate (MoDTC) was developed based on the response surface methodology. A good agreement between the predicted and actual scuffing resistance was observed within ±5% significance level.