Production and properties of copper-based powder antifriction material

Abstract

The paper examines how temperature and strain rate influence the deformation of a porous powder billet made of an antifriction material. Copper and nickel-based alloy powders produced from industrial waste are used as the initial material. The ultimate strain in compression is established and used to calculate the mold sizes in tool development. Ambiguous temperature dependence of the mechanical and antifriction properties is obtained. Temperature and strain rate that ensure satisfactory mechanical and antifriction properties are found. Processes for producing parts from the antifriction material are proposed.Powder antifriction materials have been increasingly used in industry along with compact alloys. The replacement of nonferrous metal compact alloys with copper-based antifriction materials serves two purposes: saves resources and increases the reliability and lifetime of friction units [1,2]. Copper-based powder materials are somewhat inferior to cast ones in their mechanical properties because of pores, but their performance characteristics, especially wear resistance, are much better [3]. Materials based on nonferrous metals are expensive and not readily available and require flood lubrication in operating units.This paper determines the strain rate and temperature for forming porous powder billets made of antifriction material produced from industrial waste.To make antifriction material, copper powder was used. This powder was produced from waste of M1 conductors as follows. The waste was annealed at 800°C in a hydrogen-containing medium, reduced in a knife grinder, and insulation particles were removed by air separation. The fibers 0.5 to 30 mm long were ground into powder in a hammer mill. Iron inclusions were removed by magnetic separation. Reducing annealing of the powder was conducted in generator gas at 550°C for 1 h. After the porous, easily disintegrating sponge was removed, it was repeatedly ground in a hammer mill [4]. The copper powder from waste had the following chemical composition, wt.%: Cu is no more than 99.70; Fe no more than 0.18; O no more than 0.10; Si no more than 0.10; and calcined residue (after treatment of the powder with nitric acid) no more than 0.05.To harden the material, copper powder was mixed with nickel-based alloy powder produced from waste of alkali nickel-cadmium accumulator electrodes using the following process. Positively charged lamels were removed from the accumulators, which had been disassembled by hand, immersed into weak sulfuric acid solution to remove residues of alkali solution, and then washed with water. After that, the lamels were heated to 600°C in a furnace without protective medium, cooled down in water at a rate of 60 °C/sec, and air-dried. Next, the lamels were 1 V. Dal' East

The Influence of Temperature and Deformation Ratio on Structure Formation and Physico-Mechanical Properties of Powder Materials

“…1). With the growth of preforms' heating temperature to 180-220°С the maximum deformation ratio increases; this is connected with the solid phase plasticity growth as a result of dynamical recovery [7]. At the deformation temperatures 320 and 400°С with the deformation rate of 10 and 0.1 s -1 sharp decrease of metal plasticity is observed; it is caused by the processes of dynamic strain ageing which occurs to powder materials [8].…”

“…The grain growth at the temperatures of 320 and 400°C leads to the solid phase plasticity lowering and decrease of the porous models density. In the adhesion zone the metal does not practically get deformed and the grain size corresponds to the initial, got after the static recrystallization as a result of sintering [14]. The intensification of the dynamic weakening processes leads to getting the most favorable finegrained structure of the solid phase at 180 and 600°С (Fig.…”

“…2, а). The growth of the deformation rate leads to getting a higher density at a less deformation ratio [14]. The yielding at the temperatures of 400 and 600°С, when dynamic weakening processes develop in the solid phase, leads to the formation of fine-grained homaxonic structure with the grain size of 7-9 µm.…”

“…The cylindrical preforms with the porosity of 20% were got by single-action pressing in the hydraulic press of PD-476 model with an effort of 1600 kN in the temperature interval 20-600 o C [3]. The sintering was done in the environment of flowing producer gas according to the step-bystep regime [4,5]: heating to the temperatures of 100-120°С, 200-220°С, 300-320°С 400-420°С, 500-520°С and 600-620°С with the time lag of 30 minutes at each temperature; the growth to the sintering temperature of 800°С with the time lag of 1 hour. An average porosity was 15%.…”

Development of Self-lubricating Polymeric Composites Based on PTFE

“…Lubrication-free plane bearings can be made of antifriction materials by powder metallurgy [2,9,10]. Powder metallurgy is used to make porous friction parts sintered from powders (porous bearings, multilayer, metal-plastic and metal-glass antifriction materials), which are impregnated with liquid lubricant before use in friction units [11][12][13].…”