Study on Wear Model for Piston Ring and Strengthened Cylinder Wall of Engine

Abstract

NiP electroless plating is applied to repairing engine cylinder is advanced. For practical operation conditions of engine cylinder, piston speed and lateral pressure to cylinder wall are determined as experimental factors, and abrasion value of cylinder is set as wear resistance target. According to load and speed on 1mm~8mm below top dead center of cylinder in expansion stroke, the ranges of experimental parameters are chosen. Based on the quadratic regression rotation combination method, wear resistance experiment of hardening material is designed. The wear mathematic models of NiP electroless plating is established, and three-dimensional curved surfaces for load-speed-wearing value are drawn. The results show that the NiP electrolessl plating is fit for the operating condition of cylinder, and can increase relative wear resistance of cylinder by 5 times. By analysis of wear mechanisms of hardening material and wear resistance, the material is perfect for hardening engine cylinder wall. INTRODUCTION Corrosion and wear of engine cylinder wall is serious, and the cylinder is a most heavy wear part of engine. Its attrition rate is an important mark that determines if the engine is in the big repair. So it has higher demand for surface treatment and surface repairing. Cylinder liner and piston ring are a pair of mated parts which run in high temperature, high pressure, alternate load and corrosive condition. For long term, they run in complex and alternate condition. As a result, the wear and distortion of cylinder liner affect seriously on power performance, fuel economy and durability [1-2]. Based on the modern surface hardening technology, by analysis of reasons and rules of cylinder wear, proper cylinder surface hardening methods are put forward. For high performance engine, the materials and surface processing technology of cylinder liner have been improved. It's very active to research the surface hardening technology and increase the slide characteristic of cylinder liner surface [3-4]. Surface hardening technologies of cylinder liner include nitride hardening, phosphorus hardening, thermal spraying, chromium plating, electroless nickel plating, composite plating, surface laser hardening and so on. It's an efficient way to improve the wear resistance of engine cylinder wall by the modern surface hardening technology.