Ring Wear Research Articles

Microstructure and wear resistance of Al2O3–TiB2 composite coating deposited by axial plasma spraying

Two Al2O3–TiB2 composite coatings were deposited by axial plasma spray using two types of feedstocks. One of the feedstocks was a conventional micrometre sized Al2O3–30 wt-%TiB2 composite powder from a self-propagating high temperature synthesis (SHS) process. The second was fabricated by spray drying SHSed Al2O3–30 wt-%TiB2 composite powder doped with 10 mass-% nanosized Al2O3 powder. The microstructure of the feedstocks and as sprayed coatings were comparatively investigated by scanning electron microscope and X-ray diffraction. Wear resistance of as sprayed coatings were assessed using block on ring wear test at room temperature. Results showed that Al2O3–TiB2 composite coatings were composed of α-Al2O3, γ-Al2O3, TiB2 and a small amount of TiO2. TiB2 that mostly remained in the shape of undeformed particle were dispersedly distributed in the matrix of the composite coatings. The coating from spray dried powder exhibited finer and denser microstructure and demonstrated better wear resistance than the coating from the SHSed powder under the same sliding conditions.

Implementation of Power Line MODEM for TDC Pulse Detection of SEPA

Recently, there are many cases to use a ship's engine performance analyzer(SEPA) to measure pressure in cylinder and top dead center(TDC) of piston of engine, and analyze its performance such as fuel injection time and horsepower as well as wear of piston ring. But, SEPA needs TDC pulses(T(1)∼T(n)) generated when pistons of engine are located to the TDC position(TDC(1)∼TDC(n)), these pulses are gathered from sensors connected to gear wheel of the propeller shaft in the remote distance from the measurement point. Therefore, operators need a long wire cable(WRC) to TDC detecting sensor to get these pulses, but this method is a very uncomfortable and expensive in case of installation, and it might decrease user's purchase desire. In this paper, we design and fabricate a small and inexpensive MODEM cable(M0C) so that it may be available to transmit TDC pulse generated from sensor in propeller shaft through existing power line. We also verify the facts that this MOC can be applied to SEPA and the effectiveness of the system through the experiments.

A prospective comparative study of the relationship between different types of ring and microbial hand colonization among pediatric intensive care unit nurses

Objectives The aim of the study is to assess the effect of ring wearing and ring types on hand contamination and efficacy of alcohol-based hand disinfection among nurses working in intensive care settings. Methods Hand cultures were obtained from 84 nurses providing direct patient care in intensive care units of a pediatric hospital. Colony counts were compared depending on ring wearing and the type of ring worn. Twenty-eight nurses were asked to a wear plain wedding ring, 28 to wear rings with stones and 28 not to wear any rings, starting 15 days before and continuing throughout the study. Cultures were obtained by using sterile gloves containing phosphate-buffered-saline solution (PBS) after an alcohol-based hand disinfectant was used and bacteria were identified with standard laboratory tests. Results The nurses wearing rings had more Gram-positive, Gram-negative and total bacterial colonization on their hands than the nurses without rings despite using an alcohol-based rub ( p = 0.001). When comparing the two groups with rings (plain wedding rings and rings with stones), colony counts of Gram-positive, Gram-negative and total bacteria did not differ ( p > 0.05). Conclusions Ring wearing increases the bacterial colonization of hands and alcohol-based hand disinfection might not significantly reduce contamination of the ring-wearing hands. The type of ring did not cause any significant difference on the bacterial load. Wearing rings could increase the frequency of transmission of potential nosocomial pathogens.

Appearance management Behavior and Ornament Wearing Practices in Relation to the Body Satisfaction and Image of Female College Students

The purpose of this study was to analyze the appearance management behavior and ornament wearing practices in relation to the body satisfaction and body image. The questionnaire was administrated to 261 female college students in Chungbuk area. Most respondents were dissatisfied with their bodies, especially with weight and lower part of their body. Among three factors of body image, they showed a great concern about appearance of body itself than body shape management and physical attractiveness. Most female students attempted ear-piercing and hair dyeing as appearance management behavior. They preferred to wear earrings, necklaces and rings, in the order. There was a significant relationship between body satisfaction and body image. Also, there were significant relationships among body image, appearance management behavior, and ornament wearing practices.

Quantification of the abrasive wear of a gold wedding ring

Pieces of gold jewellery, especially rings, are known to suffer continuous abrasion during the time they are worn. This fact causes troubles in chemical analyses, because analytical methods that are sensitive in the determination of gold, especially Neutron Activation Analysis (NAA), are often faced with contamination of gold from human fingers. Since no other piece of jewellery is worn more often and regularly than wedding rings, quantification of the abrasion of a wedding ring is necessary. In this study, the abrasion of an 18 carat gold wedding ring was quantified by weighing the ring weekly over the period of one year. The composition of the ring (75 Au - 15 Ag - 10 Cu) was determined using NAA. In one year, the ring lost 6.15 mg (0.39 mm3) 18 carat gold due to abrasive wear. The highest abrasion could be observed in the course of vacation on the beach, where obviously the friction with sand increased the abrasion. Gardening and skiing also result in increased abrasive wear. However, the author suggests not wearing rings in analytical laboratories to avoid this contamination.

Friction and wear bench tests of different engine liner surface finishes

Six different bore finishes of combustion engines were bench-tested against PVD-coated rings. Ring and liner specimens were removed from actual Heavy-Duty Diesel engine. The test was conducted in a CETR UMT-2 reciprocating tester. Current bore honings, e.g. slide honing, as well as recently developed structured laser were tested. For friction bench tests, the specimens were tested at different reciprocating speeds and loads. When lubricant condition approached the boundary regime (speed/load tending to zero), most of the finishes showed the usual boundary friction coefficient ∼0.11. When the conditions tended to the hydrodynamic regime, the specimen removed from the non-laser region of the laser-structured finish showed a remarkably low friction coefficient, followed by the laser-structured ones. For wear bench tests, the lubricant was doped with hard particles, and higher load and speed were used to accelerate the wear rate. Wear tests ran for 4 h and, as expected, friction coefficient reduced during the wear test due to break-in. In general, friction during the wear test followed the friction test ranking. The remarkable exception was the UV laser finish, which initially presented one of the highest coefficient and after 0.5 h of testing turned to be one of the lowest. Liner and ring wear was measured post-test by profilemeter. In general, the smoother surfaces presented lower ring and bore wear. Greenwood asperity parameters and Patir and Cheng flow factors were calculated from two measured surfaces. A computer model was applied to calculate the oil film thickness and friction for the different speed and load conditions. The calculated friction results showed good adherence to the measured data.

Adhesive and abrasive wear behaviour of TiC alloyed, sintered, austenitic stainless steels

This study examines abrasive and adhesive wear behaviour of austenitic stainless steel and its TiC alloyed composite produced through powder metallurgy technique. Abrasive wear tests have been carried out using a pin on disc wear tester under loads of 10, 20 and 30 N. For adhesive wear tests, a block on ring wear tester has been used under loads of 20, 40, 60 and 80 N. A possible correlation between the hardness, microstructure and wear behaviour of the samples has been investigated. The abrasive wear tests have revealed that the highest rate of mass loss occurred in the austenitic matrix stainless steel sample; also, mass losses decreased with an increased rate of reinforcing material in the composite. In adhesive wear tests, interparticle spacing developed from severe wear and extreme plastic deformation under heavy loads; however, at low loads, oxidation type wear was shown to be dominant.

Testing friction and wear of the tribosystem piston ring and cylinder liner outside of engines

AbstractAn OEM‐driven working group started in January 2004 to elaborate the philosophies, concepts and test procedures for testing piston ring and cylinder liner materials as well as engine oils outside of engines using the SRV (abbreviation for German: ‘Schwingung, Reibung, Verschleiß’; in English: ‘Oscillation, Friction, Wear’) test equipment. The different SRV test philosophies in use by OEMs are compiled. The working group focuses on (i) ASTM fuel economy sequence by ageing oils; (ii) friction and wear in the top‐dead‐centre region under mixed/boundary lubrication; (iii) extreme pressure load under mixed/boundary lubrication; and (iv) hydrodynamic friction. Tribological test results and precision data are presented. Copyright © 2007 John Wiley & Sons, Ltd.

Effect of La2O3 on microstructure and sliding wear properties of TiC4 ceramic coating produced by electrical discharge method

The method of electrical discharge coating with TiC4 ceramic layer in an ordinary electrical discharge machining (EDM) tool was studied. TiC4 ceramic layer was deposited on No. 45 carbon steel substrate by EDM technique. TiC4 ceramic coatings with different contents of lanthanum oxide were fabricated on No. 45 carbon steel substrate. The microstructures of the clad coatings were examined and tested for chemical composition, phase structure, friction and wear properties. Scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, hardness testing, block on ring friction and wear testing were carried out separately. Experimental results show that TiC4 ceramic coating can be deposited on a substrate of carbon steel, and the electrode doped with rare earth lanthanum oxide helps to refine coating’s microstructure and enhance the coating’s density. When the content of lanthanum oxide is increased to 0˙5%, the clad coating shows the best antiwear ability, wear resistance can be increased by three times and the friction coefficient can be decreased by 10%. If the content of lanthanum oxide exceeds that proportion, the coating’s wear resistance decreases significantly.

Impact of a Single Plain Finger Ring on the Bacterial Load on the Hands of Healthcare Workers

To investigate the impact of a single plain finger ring on the number and types of bacteria on the hands of healthcare workers (HCWs). Nonequivalent control groups, posttest only (preexperimental). A total of 121 HCWs wearing 1 plain ring and 113 HCWs wearing no rings had both hands sampled by the "glove juice" technique. Quantitative culture of the samples was performed and microorganisms were identified. Two Norwegian acute care hospitals. A total of 234 HCWs who had physical contact with patients. Total bacterial counts did not differ when hands with rings and hands without rings were compared, both according to nonpaired analysis (which compared the ring-bearing hands of ring-wearing HCWs to the hands of HCWs who did not wear rings [P=.661]) and according to paired analysis (which compared the ring-bearing and ring-free hands of ring-wearing HCWs [P=.071]). Staphylococcus aureus was recovered from 18.6% of the hands sampled, belonging to 26.9% of the HCWs, but neither paired nor nonpaired analysis showed any association with ring wearing. Gram-negative bacteria were recovered from 20.3% of the hands sampled, belonging to 28.6% of the HCWs. Ring-wearing HCWs were significantly more likely to be carriers of Enterobacteriaceae (P=.006), but paired comparison of the ring-bearing and ring-free hands of these HCWs did not show significant differences (P=.180). Carriage of nonfermentative gram-negative rods did not differ between the 2 groups, by either paired or nonpaired analysis. Wearing a single plain finger ring did not increase the total bacterial load on the hands, nor was it associated with an increased rate of carriage of S. aureus or nonfermentative gram-negative rods. However, plain rings were associated with an increased rate of Enterobacteriaceae carriage.

A Tribological Study for an Increased Coefficient of Friction in the Extraction of Sugarcane Juice

Historically, the roughening of the surface of sugarcane mill roller shells has been done by a shielded metal arc-welding process (SMAW), which is called “arcing” in the sugar industry. In this method, discrete weld globules are deposited on the grey cast iron mill roller shell surface, a process that has proven inefficient and expensive. In this investigation, the surface of the grey cast iron samples were sprayed using an electric wire arc-spraying machine. The coatings were characterized for their hardness, coefficient of friction, and corrosion resistance. A modified block and ring wear testing machine was used with bagasse as the counterface material to simulate the sucrose juice extraction process employed in the sugar cane industry. The results of the study indicated that an optimum coefficient of friction could be obtained while achieving satisfactory hardness and high corrosion resistance. Therefore, the results implied that arc spraying is a potential candidate to replace arcing in modifying the surface of the sugarcane mill roller shells.

ニート菜種油を燃料としたディーゼルエンジンの研究

It is effective to suppress carbon dioxide emission that engines utilize biomass fuels. Two experimental studies on the engine performances operated with a neat rapeseed oil are conducted. The first experiment is to clarify the performance of the diesel engine operated by seven kinds of neat rapeseed oil which were taken at the end of seven refinement stages in the manufacturing process. The experimental data show that the seven kinds of oil have the potential of practical application. The second experiment is to clarify the generation behavior of the deposit in the cylinder and the influence on the engine performance. The clearance volume of the tested engine was decreased until 700min, and the compression ratio was increased by the deposit generation. The Bosch smoke unit was not increased by the deposit generation. Although the slight increase in the consumption of the lubrication oil was detected, the piston ring wear was even less than that in the diesel fuel operation.

204 2ストローク機関におけるシリンダ・リングの摩耗特性とシリンダ壁面油膜からの潤滑油特性(機素潤滑設計I)

204 2ストローク機関におけるシリンダ・リングの摩耗特性とシリンダ壁面油膜からの潤滑油特性(機素潤滑設計I)

Stress-corrosion cracking of reactor feed pump wear rings

Stress-corrosion cracking (SCC) is observed in machine components when an optimal combination of stress levels and environmental conditions is present in susceptible material. An interesting case history of intergranular SCC failure is presented in this paper. This failure occurred in wear rings that were shrink-fitted on the impellers of a multistage horizontal feed pump during the project procurement phase. After manufacture and assembly, two pumps were performance-tested in the supplier's test loop for a combined total of approximately 600 h. The test duration lasted for approximately three months. During this duration, the two pump internals were not absolutely dry and were exposed to an indoor environment in the supplier's test plant. After the completion of the tests, the pump internals were inspected, cleaned, dried, and packaged before air freighting to the reactor site. The pumps were in storage at the site for approximately two months. When the pumps were opened for inspection, two wear rings on each of the pumps were cracked. This paper summarizes the results of the studies to evaluate the root cause of the wear ring failures and the corrective actions implemented to avoid similar failures.

A Model for Wear and Friction in Cylinder Liners and Piston Rings

A one-dimensional elstohydrodynamic mixed lubrication wear and friction model is developed. The model can predict the effects of surface roughness, asperity contact, temperature-pressure-viscosity on wear, lubrication, and friction of the piston rings and cylinder liner. Wear is predicted based on the surface asperity contact pressure. The cylinder bore wear and the ring pack friction during an engine break-in are simulated and compared with the experimental results. The influence of cylinder wall temperature and surface roughness on friction and wear is investigated. The ring pack friction due to oil viscous shearing and asperity contact is found to reach its minimum at a certain oil temperature.

Ring wear monitoring in IC engines: an acoustic emission approach

Monitoring the condition of the engine compression ring in an engine operation is very important since it affects the engine performance. One of the most promising ring wear monitoring methods is based on the analysis of acoustic emission (AE) signals, which is an extremely powerful technique that can be deployed in a wide range of applications of non-destructive testing [Vallen Systeme (2000)]. This technique is already used for monitoring tool wear almost in all machining operations, but in this study, the AE signals were applied for monitoring ring wear in internal combustion (IC) engines. The AE signals generated in the ring sliding zone are very sensitive for correlation with ring wear, which in turn affects ring performance. This study was carried out with a single compression ring mounted on the piston. The AE signals were analyzed by considering signal parameters such as ring down count and RMS voltage [Krzysztof Jemielniak (2000) J Mater Process Technol 4752:1–6]. Analysis showed that the AE signal technique is applicable for ring wear monitoring in IC engines.

Tribological performance of nano-Al 2O 3 reinforced polyamide 6 composites

Nano-Al 2O 3 and micron Al 2O 3 reinforced polyamide 6 composites (PA6/Al 2O 3) were prepared via in situ polymerization. The effects of nano-particle content and wear condition on the tribological properties of the composites were measured using a MM-200 block on ring wear tester. The worn surface was investigated with a scanning electronic microscope and a metallurgical microscope and the wear mechanism was proposed. It was found that nano-Al 2O 3 improved the wear resistance of monomer casting polyamide 6 with the optimal content of nano-Al 2O 3 being approximately 3 wt.%. The wear rate of PA6/Al 2O 3 nano-composite was lower than that of the composite with micron Al 2O 3 and increased slowly while its friction coefficient decreased gradually with load. However, the friction coefficient of the composite was somewhat larger than that of monomer casting polyamide 6 and lower than that of the composite with micron Al 2O 3.

Cause and effect assessment after a complex failure of a large ethylene compressor

A rusted cylinder liner and excessive wear of piston rings forced several maintenance disassemblies in a 1000 kW ethylene reciprocating compressor. Several months later the compressor failed due to growth of cracks in the crosshead of one of the cylinders. The initiation site was located in material defects near a stress raiser. In order to identify the root cause of the failure, crack growth time calculations were required. The applied stress field near the initiation sites and along fatigue paths were FEM estimated. Stresses vary steeply and become partly compressive along a large part of one of the fatigue crack paths. A recently developed weight function based numerical method was used to assess total fatigue crack growth time; this method also predicts the shapes of the crack front during propagation. Fatigue crack initiation was traced to a disassembly six months before final failure, which was found to be a joint result of non-conformities in manufacture and maintenance.

Wear and loss of rings used on Razorbills Alca torda – further caution in the estimation of large auk survival

On Græsholmen in the central Baltic Sea, 3,583 Razorbill Alca torda chicks were ringed with triangular Incoloy rings, and about half the birds were subsequently resighted. The resightings were used to calculate rates of turned rings, and 119 retrieved rings were used to calculate rates of wear and ring loss. At 1.7%, the rate of turned rings was much lower than reported among Common Guillemots Uria aalge in Britain, most likely because the Razorbill rings were fitted with soft wax at the time of ringing. The mean annual rate of metal loss of rings on birds for 3–9 years was 1.51%. Ring loss due to abrasion was 50% by year 14 with no ring lasting longer than 24 years, thus severely biasing survival estimations based on ringing data.

405 2ストローク機関におけるシリンダおよびリングの摩耗特性(応用熱工学II)

405 2ストローク機関におけるシリンダおよびリングの摩耗特性(応用熱工学II)