Quality of polymeric tribocompound powders and its influence on microstructure and mechanical/tribological behavior of 3D manufactured parts

Abstract

In this study, a structural and functional analysis was conducted to investigate antifriction multicomponent polymer composites on the basis of ultrahigh-molecular polyethylene (UHMWPE) developed as feedstocks for additive manufacturing of friction parts operating under extreme conditions. The aim was to make UHMWPE extrudable by selecting appropriate polymer plasticizers. An algorithm is proposed for the development of extrudable UHMWPE-based composites with a minimum amount of experimental data available. The algorithm determines the control parameters that provide required characteristics of multicomponent polymer materials and thereby ensure the achievement of desired tribological, mechanical and processing properties. The dependence of the experimentally determined characteristics versus the control parameter values is analyzed, and corresponding response surfaces are constructed in the state space. The surfaces reveal the range of the control parameter values that ensure the achievement of specified properties. The algorithm is applied to select an optimal composition of the ternary “UHMWPE+ 17 wt% HDPE-g-SMA + 12 wt% PP” mixture, whose tribological and mechanical behavior is similar to that of unfilled UHMWPE, but the melt flow is good enough for 3D printing. A comparative study is carried out on structural, mechanical and tribological properties of the multicomponent “UHMWPE+ 17 wt%HDPE-g-SMA+ 12 wt% PP” composites fabricated by FDM printing and hot pressing. It is shown that the tribological and mechanical properties of 3D-printed extrudable UHMWPE-based composites exceed the properties of composites obtained by compression sintering, which is due to the formation of more homogeneous permolecular structure with increased crystallinity. The tribological characteristics of the 3D-printed composites are studied under various friction test conditions (P*V). The composites are proposed as suitable for friction parts operating in a wide range of speeds and loads.