Preparation And Properties Of Cu/Cu-MoS₂Self-lubricating Composite

With the development of aerospace, space and new energy industries, thetraditional metal cannot afford the requirement under some special hard conditions. Inthis case, self-lubricating (SL) materials exhibit superior anti-friction characteristics. Itis significance to study and exploit self-lubricating composites with good physical andmechanical properties which can be used under hard conditions.The Cu/Cu-MoS2self-lubricating composites in this topic was prepared bypowder metallurgy method. The surface layer was added some lubricating material, thebasal material was copper. The two different materials were combined by sintering toget a new self-lubricating composite. Half of the material had high mechanicalstrength and electrical conductivity and the other half material has good tribologicalproperties. The new material has better than ordinary composites, because it hastransition interface. The transition interface makes the composition of the ends mutualpenetration and the composite has good interface bonding, and giving full play to theadvantages of special performance on both ends.In this paper，the Cu/Cu-MoS2self-lubricating composites was prepared by coldisostatic pressing sintering and vacuum hot pressing sintering process. Themicrostructures, mechanical properties, electrical conductivity and density werecharacterized by a variety of testing techniques. Wear Resistance was tested by High-temperature friction and wear sampler. Studied and discussesed the the anti-friction ofself-lubricating composite material properties and wear mechanisms. The results showthat:1. The interface of Cu/Cu-MoS2self-lubricating composite materials prepared bycold isostatic pressing was combined well. There was a transition layer and nomutations between the interfaces. When the content of MoS2is3%, the composite both had excellent hardness and good electrical conductivity. The hardness of thecomposites can reach126.5HBW and the conductivity reached40.55Ms.m-1.2. With the increase of MoS2, the density and electrical conductivity of thecomposite decreased, the hardness increased. When the content of MoS2increasedfrom2%to6%, the density decreased2.77%and the electrical conductivity decreased31.9%, the hardness increased42.97%. At the same time, the tensile strength of thecomposites reduced30.9%. And the fracture mechanism was transformed fromcompletely ductile fracture to ductile fracture with brittle fracture.3. In the process of sintering, Cu reacts with part of MoS2, the sintered productsof wear-resisting layer mainly are complex compounds of Cu, Mo and S, andelementary Mo. As the change of MoS2, the copper molybdenum sulphur compoundsand copper sulfide changed regularly. The sintering products tended from singleCu1.84Mo6S8to Cu1.84Mo6S8、Cu5.4Mo18S24、Cu2S and Cu31S16.4. Compared with cold isostatic sintering process, the hardness of Cu/Cu-MoS2self-lubricating composites prepared by vacuum hot pressing had improved obviouslyand the conductivity was no significant change. After milling40h, the hardness of theresistance layer reached148.6HBW and the electrical conductivity was40.25MS.m-1.5. The results of high temperature vacuum friction and wear test show that: whenthe temperature increases, the lubricating films are more likely to play a role of anti-friction. The wear mechanisms are mainly adhesive wear and abrasive wear, but thedominant wear mechanism in different temperatuer is different.In conclusion, the hardness and conductivity of Cu/Cu-MoS2self-lubricatingcomposites prepared by vacuum hot pressing process and after ball-milling40h canmatch up excellent. The basal material and wear-resisting layer combined well. Thecomposite has excellent self-lubrication properties in high temperature environment.