Assessment of engine valve materials

International Journal of Mechanical Engineering and Robotics Research

The paper aims to study the thermal stresses on an exhaust valve body with and without using the Thermal Barrier Coating technique (TBC) in the valve face region. A 2-dimensional model is created for the numerical analysis. The work is carried out with the aid of the ANSYS-APDL package. The procedure of the numerical analysis is divided into two processes. The first process is the thermal analysis to obtain the temperature values, which are set up as thermal loads for the structural analysis in the second process. The coating of the valve is carried out through three steps of analysis by selecting a single layer of TBC, a double layer of TBC, and a triple layer of TBC. Three types of TBC materials are taken in this work, which are SiO2, Al2O3, and ZrO2. The location of TBC type for the double and triple cases is taken into consideration, in the steps of analysis of double and triple design of exhaust vale coating is done by changing of the material type of TBC which it is on the upper or lower concerning the valve face. The results showed that using the SiO2 material as a TBC in the case of single, double, and triple coating of the exhaust valve face gives a low value of thermal deformations and thermal stresses. The stresses in steel alloy in cases without and with TBCs as compared to titanium valve showed a good reduction in thermal stresses for the titanium aluminide exhaust valve.

2018

with the aim to improve the engine efficiency and to reduce the greenhouse gas emission, hydrogenated Diamond-Like Carbon (HDLC) coating are used in engine component that are prone to excessive sliding friction and transient heat source. The valve train system in the engine is subjected with the above stress condition. The HDLC coating has significant properties of low co-efficient of friction, better corrosion resistance and also acts as thermal barrier. To evaluate the influence of the DLC coated valve, the performance, emission and combustion characteristics is compared with the TiN coated and conventional valve. TiN a hard and inert material which is also used as coating for engine components. Applying TiN as thin coating to the metal substrate helps to enhance mechanical and thermal properties of the base metal. The DLC and TiN films are deposited on AISI 5140 steel substrate by means of magnetron sputtering technique for various thicknesses of 2, 3, 4 , 5 and 6 microns. The te...

Poppet engine valve is a precision engine component which blocks gas flow ports and controls the exchange of gases in internal combustion engines. The functionality of the valve is to seal the working space inside the cylinder against manifolds by continuously opening and closing of valve according to valve timing diagram. Existing difficulties with poppet engine valve being that it tend to fail due to fatigue after executing about 300 million operating cycles. Thus this research paper aims to establish effect of varied materials and Geometric parameters on mechanical properties of poppet engine valve to improve its performance over life and fatigue life using Ansys software.

Valves are the most important and critical part of an Internal Combustion engine. Many factors matters while designing the intake and exhaust valve of an engine such as gas inflow, material properties, oxidation characteristics, fatigue strength, thermal strength, configuration of coolant flow and cylinder head. In this, we had made the model of Inlet valve of the two wheeler in NX and had analysed it in the ANSYS. First, we had selected the different materials that were suitable for the Intake valve. After some research, we had selected two materials (SUH3, SAE1541) which can perform better for Intake valve. After this, we had performed thermal, thermal-coupled structural analysis. In this, we observed the temperature distribution over the Intake valve and deformation of Inlet valve.

Mechanically operated poppet valves are used, both as inlet and exhaust, for most conventional automotive engines in passenger cars. These valves are subjected to high temperatures throughout their operating cycle. A valve originally designed for a gasoline engine, when used for an LPG fueled retrofitted engine, goes through considerable mechanical damage, corrosion, erosion, wear and tear. It also demonstrates significant changes in its microstructure. This investigation focused on microstructure analysis and quantitative metallography of such inlet and exhaust valves using Atomic force microscopy (AFM) technique. The surface morphology of the valve material was studied and AFM measurements were used for quantitative characterization of the structure as also to gain useful information about crystallographic orientation of individual grains, the formation of cracks, identification of potential crack initiation and fracture sites, etc. A comparative evaluation of microstructure of worn - out valves with new valves was also carried out

Gazi University Journal of Science, 2010

The exhaust valves of a diesel engine are exposed to thermal and mechanical overstress which may be sources of valve failures. The exhaust valves usually fail as a result of different failure modes such as wearing, fatigue and corrosion. In order to describe these modes a failed exhaust valve which was belonged to a heavy-duty diesel engine is investigated. The investigation of the failure was carried out by using several experimental tests including optical emission spectroscopy, optical microscopy, scanning electron microscopy SEM and EDX. It was found that the carbon content of the material of the failed valve decreased. Angular titanium phases were found in microstructure of the material of the failed valve. Fuel-born vanadium and chromium carbide were detected on the surface of the valve. It was concluded that the valve was broken down before its expected service life.

Engineering Failure Analysis, 2018

This work investigates the causes of excessive wear occurring at the rocker arm/pushrod and rocker arm/valve interfaces of a diesel engine for industrial cleaning machines, after only 1000 hours of engine operation. In this engine, the recent replacement of tappets by hydraulic valve lifters not only reduced the running time but also required supplementary maintenance. The chemical composition of the worn components was verified by optical emission spectroscopy. The microstructures, mechanical properties and surface textures were determined by optical microscopy, Vickers hardness and non-contact 3D profilometry. To evaluate the wear mechanisms, the worn surfaces were analyzed by scanning electron microscopy with energy dispersive spectroscopy. The results indicated nonuniform wear damage at the rocker arm/valve interface, probably due to a misalignment of valves with respect to valve seat inserts. For rocker arms and pushrods, improper austenitization parameters and/or unsuitable design of the inductor left some free ferrite, responsible for non-compliance with required specifications for the induction hardening treatment. All worn surfaces were characterized by material removal by scuffing; initiation of fatigue cracks was also observed at the rocker arm/valve interface, and probably erosive cutting occurred at the rocker arm/pushrod interface.

Journal of Failure Analysis and Prevention

This work investigates the causes of wear occurring at the engine valve tip end after 400 hours of engine operation. Fatigue wear was observed on the valve tip at the product development stage of the engine, which is going to be used in an automotive vehicle. Valves were assembled on a gasoline/CNG fuel-based four-cylinder IC engine. In this engine, tip end wear was prominent during high-speed testing conditions as compared to other types of engine tests. The chemical composition of worn surfaces was verified by spectroscopy. The microstructures, grain sizes and surface roughness were determined by optical microscopy and surface roughness tester. To evaluate the wear mechanism, valve tip end worn surfaces were analyzed using Scanning electron microscopy. The SEM analysis indicates the initiation of micropits and subsequent propagation of the fatigue wear during engine operating conditions. The residual stresses were measured at valve tip end surfaces and subsurfaces using X-ray diff...

The Journal of Engine Research, 2012

ARTICLE INFO This paper presents a failure analysis on a failed intake valve in a gasoline engine. During an endurance test, an intake valve was broken and caused some damages on the piston. Material examinations (by a light microscope and also a scanning electron microscope) were conducted on the fracture surface of the intake valve shaft. Results showed that no pores or defects could be observed and the microstructure and the hardness of the material were conformed to the specification (the standard map extracted by the manufacture). But a mechanical factor caused the damage which consisted of a reversal bending load due to the misalignment of the valve shaft. The misalignment was caused by the thermal deformation in the valve shaft. The engine was working in a hot condition. Also, it was a reversal condition (with zero mean stress) due to the rotation of the valve shaft during engine working. Also, the fracture surface demonstrated beach marks due to cyclic loadings. In this case...

International Journal for Research in Applied Science and Engineering Technology IJRASET, 2020

Engine is the heart of automobiles and valve mechanism is the heart of engine. There are two types of the valves are used in internal combustion engines which are intake valve and exhaust valve. Intake and exhaust valves are used to control the flow of intake fresh charge and Exhaust flue gases alternatively in Engine. They are used to seal the working space inside cylinder against the manifold and they open and close by means of what is known as the Valve gear mechanism. Exhaust valve work well in engines because the pressure inside the combustion chamber pushes valve against the seat, sealing the chamber and preventing leaks during this cycle exhaust valves are exposed to high temperature and pressure which will affect the life and performance of the engine. The aim of the project is to design an exhaust valve with a suitable material along with the three different fillet radii for a four-stroke diesel engine by using Finite Element Analysis. In exhaust valve we have considered Aluminium 7068 alloy, Silicon carbide reinforced Zirconium di-boride and Carbon fiber composite material. In this we observe the results of existing exhaust valve's stress, strain and total deformation values are compared to the modified exhaust valve design are shows tremendous change in stress, strain and total deformation of the composite material.