Valve Seat Inserts Research Articles

Impact Wear Characteristics of Valve and Valve Seat Insert Materials for Engines at High Temperature. Plane Impact of Martensitic Heat Resistant Steel SUH3 against Fe-Base Sintered Alloy.

In order to simulate the wear of the valve and valve seat insert of actual engines, an impact wear test is conducted using a ring of JIS SUH3 steel valve material, and a disk of sintered alloy valve seat insert material. Test conditions are as follows: impact energy is 0.588J ; atmosphere is normal air; temperatures are room temperature, 200°C and 400°C; sliding speed is from 0 to 0.8m/s. Under these conditions, for impact only without sliding, very low wear is observed. Under impact with sliding conditions, at room temperature and 200°C, a bright worn surface is observed. With a sliding speed over 0.4m/s the wear rate is severe. However, at 400°C, oxidation occurs and no acceleration of wear rate is observed at all sliding speeds. At any sliding speed and test temperature, the sintered alloy disk wear is more severe than that of the SUH3 steel ring. These results can be explained taking into consideration the oxidation and mechanical properties of these materials.

バルブシート用焼結モリブデン鋼の特性

Mechanical properties of PM alloy steels containing 5%No, 5%Ni, 5%Co and 6%Cr were investigated in order to develop an intake valve seat insert for automobile engines. After the rig wear test, corrosion test and actual engine tests, the new intake valve seat insert material was developed. The material was 5% No PM molybdenum steel made through the transient liquid phase sintering, in which the copper phase is precipitated uniformly in the matrix. This material can be used for both leaded and unleaded gasoline engines.

PM HSS for aerospace automotive and cutting tool applications

A new image for ferrous PM emerged some 20 years ago with the economically successful sintering of HSS cutting tools to net shape and near full density with acceptable and uniform microstructures, especially for single point turning. This process relies on cheap water atomized powders. Simultaneously processing of gas atomized powders by HIPing was perfected and superior quality materials, especially with high alloying additions, improved cleanliness and finer, uniform microstructures became available. Amongst subsequent developments CVD and PVD coating of HSS with TiN, continuous sintering and copper infiltration of HSS for valve seat inserts and binder assisted powder extrusion of water atomized T15 for oil hole drills should be mentioned. Ferrous PM is no longer synonymous with ‘dirty, porous and cheap’. Andrew Wronski and his fellow researchers describe three types of application relating to machining, automotive valve train and aerogas turbine bearings.

Some aspects of the future of powder metallurgy

Some of the developments in PM materials presented at the 1989 Institute of Metals PM Conference, (9–11 October 1989) are reviewed. Keynote addresses on rare earth magnets, surface treatments, and high performance materials are covered together with developments in valve seat inserts (VSI's), soft magnetic materials, and spray forming which were reported in workshop sessions.

Ceramics Technology—Application to Engine Components

In the development of engine components a number of special techniques are used to combat the hostile operating environment which usually includes high and cyclic forces, high and cyclic temperatures, sliding and often corrosion and/or erosion. Examples of the use of these techniques, namely the development of special materials for substrate and surface, of mathematical modelling verified by telemetry, and of special machining, to solve the problems of the operating environment, are given in respect of pistons, piston rings, cylinder liners, bearings, camshafts and valve seat inserts. It is noted that of the above techniques the development of special surface and substrate materials provides the most universal assistance. The application of materials technology to surface and substrate is illustrated with respect to ceramics, including silicon nitride, silicon carbide, zirconia and alumina. Applications under development include insulation, improvement of wear resistance, reduction of mass, increase of operating temperature and the reinforcement of metals, for example, reinforcement of aluminium alloys using alumina fibres incorporated by squeeze casting. The several means open to improve the properties of gravity cast aluminium silicon alloys are reviewed and the improvement of properties obtainable by squeeze casting without reinforcement are illustrated. The further enhancement of these properties by the design of an appropriate fibre reinforcement system, incorporated by squeeze casting, is then described. Its application to the reinforcement of a combustion bowl subject to high thermal stress is discussed and the performance of the resulting piston in relation to unreinforced pistons is described. In conclusion the market, product and process aspects of the development are correlated to demonstrate its overall value and to identify further applications.

CERAMICS TECHNOLOGY

In the development of engine components a number of special techniques are used to combat the hostile operating environment which usually includes high and cyclic forces, high and cyclic temperatures, sliding and often corrosion and/or erosion. Examples of the use of these techniques, namely the development of special materials for substrate and surface, of mathematical modelling verified by telemetry, and of special machining, to solve the problems of the operating environment, are given in respect of piston rings, cylinder liners, bearings, camshafts and valve seat inserts. It is noted that of these techniques the development of special surface and substrate materials provides the most assistance. The application of materials technology to surface and substrate is illustrated with respect to ceramics, including silicon nitride, silicon carbide, zirconia and alumina. Applications under development include insulation, improvement of wear resistance, reduction of mass, increase of operating temperature and the reinforcement of metals, for example reinforcement of aluminium alloys using alumina fibres incorporated by squeeze casting. The several means open to improve the properties of gravity cast aluminium silicon alloys are reviewed and the improvement of properties obtained by squeeze casting without reinforcement are illustrated. The further enhancement of these properties by the design of an appropriate fibre reinforcement system, incorporated by squeeze casting, is then described. Its application to the reinforcement of a combustion bowl subject to high thermal stress is discussed and the performance of the resulting piston in relation to unreinforced pistons is described. In conclusion the market, product and process aspects of the development are correlated to demonstrate its overall value and to identify further applications.

CERAMICS TECHNOLOGY

In the development of engine components a number of special techniques are used to combat the hostile operating environment which usually includes high and cyclic forces, high and cyclic temperatures, sliding and often corrosion and/or erosion. Examples of the use of these techniques, namely the development of special materials for substrate and surface, of mathematical modelling verified by telemetry, and of special machining, to solve the problems of the operating environment, are given in respect of piston rings, cylinder liners, bearings, camshafts and valve seat inserts. It is noted that of these techniques the development of special surface and substrate materials provides the most assistance. The application of materials technology to surface and substrate is illustrated with respect to ceramics, including silicon nitride, silicon carbide, zirconia and alumina. Applications underdevelopment include insulation, improvement of wear resistance, reduction of mass, increase of operating temperature and the reinforcement of metals, for example reinforcement of aluminium alloys using alumina fibres incorporated by squeeze casting. The several means open to improve the properties of gravity cast aluminium silicon alloys are reviewed and the improvement of properties obtained by squeeze casting without reinforcement are illustrated. The further enhancement of these properties by the design of an appropriate fibre reinforcement system, incorporated by squeeze casting, is then described. Its application to the reinforcement of a combustion bowl subject to high thermal stress is discussed and the performance of the resulting piston in relation to unreinforced pistons is described. In conclusion the market, product and process aspects of the development are correlated to demonstrate its overall value and to identify further applications.