Boundary conditions analysis of the possible use of bushings made from copper composite materials for a towing vehicle’s chassis

The paper analyzes the possible boundary conditions for the application of new type of bushings in the vehicle’s chassis. The bushings have been manufactured from the copper-based antifriction composite material alloyed by nickel and molybdenum, with the addition of CaF2 as a solid lubricant (DN5M3KF9). The structure and tribotechnical properties at heavy loaded reversing friction (the temperature of 400-6000С and pressure up to 6.0 MPa in air) have been examined. The study focuses on the distribution of CaF2 in the composite with a Cu–Ni–Mo matrix, its role in self-lubrication of the material, and the behavior of CaF2 in the friction area under extreme operating conditions. It was shown that the solid lubricant is evenly distributed over the contact surfaces as it piles up over the entire friction area during heavy loaded reversing friction. It is established that the tribofilms formed in the presence of the CaF2 solid lubricant provide high wear resistance. Tribological properties allow for extending the application boundaries of the new bushings based on copper in the vehicle chassis for towing artillery guns.

Influence of the Reinforcing Elements on the Wear Behavior of Al/(Sic+Graphite) Composites Elaborated by Spark Plasma Sintering Technology

The paper presents the experimental results regarding the influence of the reinforcing elements on the wear behavior of Al-matrix composites discontinuously reinforced by SiC and Graphite. This antifriction composite material is processed by Reactive Mechanically Alloyed and then by Spark Plasma Sintering technology. In order to optimize the processing technology, especially the sintering parameters, the Spark Plasma Sintering process was applied because of its advantageous aspects: lower sintering temperatures, shorter sintering time and higher properties values of the sintered material vs. the corresponding ones obtained by the classical sintering route. The authors realized a comparative analysis on the wear behavior of the researched composite materials.