“…This indicates the possibility of adhesive wear, which has also been reported in previous researches. 1,7,14 Figure 15(a) to (f) SEM micrographs of seat insert worn surfaces; (g) EDS results; (h) schematic of wear mechanism.EDS: energy dispersive spectroscopy; SEM: scanning electron microscope.…”
Section: Resultsmentioning
confidence: 99%
“…This means that the valve hardfacing alloy material was transferred to the seat insert surface and that the adhesion was an oxygen-rich compound. However, according to the results of Mascarenhas et al., 14 valve seat insert materials are detached and adhered on the valve’s surfaces. Hence, the transferring behavior of materials between the valve seating surface and seat insert indeed existed.…”
Section: Resultsmentioning
confidence: 99%
“…Mascarenhas et al. 14 used loads of 6 kN and 9 kN; and the loading frequency varied from 6 Hz to 9 Hz. Lewis et al.…”
The increasingly strict emission regulations in combustion engines are raising high requirements for the engine valve train system. In this paper, a novel multifunctional wear apparatus is designed to study the performance of engine valve train components. The apparatus employs a mechanical loading system, which consists of a special eccentric wheel and disc springs that apply the combustion loads, and the contact configurations and loading conditions of valve train components are simulated. It has three test functions for different components through specifically designed fixtures. The first function aims to evaluate the interaction between the valve seating face and the seat insert at high temperatures and loads. The second function is used to study the friction and wear properties of the valve stem and the valve guide. The third function is designed to evaluate the performance of the valve seals. At last, a verification test was carried out by the proposed experimental method. A pair of new exhaust valve and seat insert is tested for the performance evaluation of the first function. The wear mechanisms acting on the pairs interface are shown to be a combination of oxidative wear, adhesive wear, as well as fatigue flaking.
“…This indicates the possibility of adhesive wear, which has also been reported in previous researches. 1,7,14 Figure 15(a) to (f) SEM micrographs of seat insert worn surfaces; (g) EDS results; (h) schematic of wear mechanism.EDS: energy dispersive spectroscopy; SEM: scanning electron microscope.…”
Section: Resultsmentioning
confidence: 99%
“…This means that the valve hardfacing alloy material was transferred to the seat insert surface and that the adhesion was an oxygen-rich compound. However, according to the results of Mascarenhas et al., 14 valve seat insert materials are detached and adhered on the valve’s surfaces. Hence, the transferring behavior of materials between the valve seating surface and seat insert indeed existed.…”
Section: Resultsmentioning
confidence: 99%
“…Mascarenhas et al. 14 used loads of 6 kN and 9 kN; and the loading frequency varied from 6 Hz to 9 Hz. Lewis et al.…”
The increasingly strict emission regulations in combustion engines are raising high requirements for the engine valve train system. In this paper, a novel multifunctional wear apparatus is designed to study the performance of engine valve train components. The apparatus employs a mechanical loading system, which consists of a special eccentric wheel and disc springs that apply the combustion loads, and the contact configurations and loading conditions of valve train components are simulated. It has three test functions for different components through specifically designed fixtures. The first function aims to evaluate the interaction between the valve seating face and the seat insert at high temperatures and loads. The second function is used to study the friction and wear properties of the valve stem and the valve guide. The third function is designed to evaluate the performance of the valve seals. At last, a verification test was carried out by the proposed experimental method. A pair of new exhaust valve and seat insert is tested for the performance evaluation of the first function. The wear mechanisms acting on the pairs interface are shown to be a combination of oxidative wear, adhesive wear, as well as fatigue flaking.
“…또한, 작동유체 속에 존재할 수 있는 입자들은 밸브 부 품들의 침식마멸 (erosive wear) 을 유발할 수 있으며 [7,8], 특히, 밸브 개폐 시 발생하는 반복적인 접촉 미 끄럼 운동은 표면파손을 유발하여 표면 거칠기를 증가 시키고 [9], 나아가 심각한 마멸을 초래한다. 이러한 밸 브의 파손 현상은 결과적으로 누유(leakage)를 유발하여 밸브 시스템 전체의 치명적인 파손으로 이어질 수 있으 므로 [10][11][12], 밸브의 수명을 향상시키기 위해서는 구성품 들의 내마모성을 고려한 설계가 요구되며 [13,14], 이에 따라 표면 열처리 및 코팅 등을 통하여 내마모성을 향 상시키기 위한 연구가 수행되고 있다 [15].…”
− The wear characteristics of metal ball and seat in a metal-seated ball valve significantly affect the performances such as leakage and valve torque. In this work, the wear characteristics of metal ball and seat are experimentally investigated. A stainless steel ball and seat with a high corrosion-resistant coating are prepared and a component level test was performed. The hardness and surface roughness of specimens cut from the metal ball and seat are measured before and after the test using a micro-Vickers hardness tester and confocal microscopy, respectively. In order to assess the wear characteristics, the surfaces of the specimens are carefully examined after the test. The confocal microscope data show that the surface roughness values of both the ball and seat increase by a factor of 3-4, which may lead to an increase in valve torque. However, the wear of the seat is found to be more significant than that of the ball. In addition, a comparison of the surfaces of the ball and seat before and after testing revealed that adhesive and abrasive wear are the major wear mechanisms. The results of this study may aid in the design of metal-seated ball valves from the tribological point of view.
“…These applications require materials with low friction and increased mechanical strength. Numerous works have been reported using various synthetic reinforcements in thermoset and thermoplastic matrices on tribology [3,4]. However, these synthetic fibers has challenges such as fluctuating cost and also accumulates as non-degradable landfill.…”
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