Prediction of lining wear life of bins and chutes in bulk solids handling operations

This paper is concerned with the prediction of lining wear life of bins and chutes in bulk solids handling plant. It focuses on abrasive wear and outlines the basic principles to be embodied in the development of a laboratory wear tester. Emphasis is given to a linear action wear tester developed jointly by the University of Twente, The Netherlands, and the University of Newcastle, Australia. The characteristics of abrasive wear in bins, hoppers and chutes are described and the application of test results to the prediction of wear life of lining materials is illustrated.     

Slurry pump side-liner wear: comparison of some laboratory and field results

The current work compares some slurry pump lab wear results with the wear found across different field applications with d₈₅ particle size ranging from 100 to 4000 μm. Side-liner wear life data has been collected for two different impeller geometries and two different material classes (cast iron and natural rubber). Different field wear patterns have been photographed and categorised on the basis of particle size. The field wear patterns showed close similarity to the lab wear patterns particularly in the areas of localised gouging. Wear rates are also compared for the different geometries. Overall trend of wear with particle size for the white iron parts was similar to the grey iron lab tests albeit at significantly lower wear rates. In general, the wear with the rubber side-liner was less at smaller particle sizes but greater for particles larger than d₈₅ of about 700 μm.     

Dynamic thermoanalytical test method for qualifying brake lining materials

A thermoanalytical test method is described for qualifying brake lining materials, based upon the recording of coefficient of friction f versus temperature T diagrams. Tests are performed at a low sliding speed, thus avoiding substantial increase in temperature due to dissipation of frictional energy. During testing, the temperature in the friction interface of a brake lining-metal ring friction couple is increased linearly with time by means of time-controlled inductive heating of the metal ring. It is shown that the method yields a ‘fingerprint’ of the brake lining material, which is characteristic for its friction-temperature behaviour as related to composition and structure and which can thus be used for identification purposes and in acceptance testing. Repeated runs in the range T_o–T_max, performed at , yield information on the f−T behaviour of lining materials which, in previous runs, have been exposed to a maximum contact temperature T_max. The method is illustrated with results obtained with a resin/asbestos and a cermet/graphite material.     

A new tribometer for friction and wear studies of dental materials and hard tooth tissues

This paper presents a new tribometer developed for a study of the tribological behaviours of dental materials and hard tooth tissues. The device simulates oral kinematic conditions and the loading produced during masticatory process. The tribometer is similar to the existing devices regarding the kinematic features, i.e. it produces an adjustable oscillating movement. However, the device machine is equipped with a unique pneumatic system of loading controlled via computer by special software called TOOTHY. The programmable system allows easy adjusting of the loading parameters such as the magnitude of normal force and its amplitude or pattern of cyclic loading. In this way different combinations of loads can be applied thus making the investigation of different wear situations possible. The device has two full bridge strain gauges for the measurement of loading and friction forces, by which the coefficient of friction is determined.The use of the tribometer is illustrated by a comparative study of tribological behaviour of human enamel subjected to two- and three-body friction, and to two different loading patterns as well. The obtained results are discussed.     

纳米晶粉末制备复合材料的摩擦磨损性能

本文研究了用机械合金化方法制备出Ｓｉ３Ｎ４／Ｆｅ基纳米晶复合粉末，用常规粉末冶金工艺烧结出试样，测试了复合材料的常温摩擦磨损性能，并对其显微组织进行了分析，认为纳米晶的界面确实机改善Ｓｉ３Ｎ４与Ｆｅ的结合强度。     

Accelerated wear testing as an aid to failure diagnosis and materials selection

The needs and advantages of accelerated wear testing are discussed, with particular reference to aerospace applications. Examples are given from recent work on plastics-based dry-bearing liners to illustrate how accelerated wear tests can provide information relevant to materials selection, identification of the main parameters influencing wear and definition of the relationships between wear, material composition and structure. Prediction of the service life of dry-bearing liners, however, presents problems and full-scale component tests are usually required     

Ceramic-ceramic composite materials with improved friction and wear properties

Dry friction and wear tests were performed with self-mated couples of SiC containing 50% TiC, Si₃N₄---BN, SiC---TiB₂ and Si₃N₄ with 32% TiN at room temperature and 400°C or 800°C.Under room temperature conditions, the friction coefficient of the couple SiC---TiC/SiC---TiC is only half of that of the couple SiC/SiC and the wear is one order of magnitude smaller. At 400°C, it exceeds the friction coefficient of SiC/SiC except at the highest sliding velocity of 3 m s⁻¹. At lower sliding velocities the wear coefficient of SiC---TiC/SiC---TiC is lower than that of SiC/SiC.The couple Si₃N₄---TiN/Si₃N₄---TiN exhibits high friction coefficients under all test conditions. At room temperature the wear volume of the self-mated couples of Si₃N₄ and Si₃N₄---TiN after a sliding distance of 1000 m is similar, but Si₃N₄---TiN shows a running-in behaviour. At 800°C the wear coefficient of Si₃N₄---TiN/Si₃N₄---TiN is approximately two orders of magnitude smaller than that of Si₃N₄/Si₃N₄, and equal to those at room temperature. At 22°C the addition of BN reduces the friction of Si₃N₄. The wear coefficient is independent of sliding velocity and the self-mated couples showing running-in. Friction and wear increase with increasing temperature. The wear coefficient of SiC---TiB₂ above 0.5 m s⁻¹ at 400°C is advantageously near 10⁻⁶ mm³ (Nm)⁻¹. With the other test conditions the wear behaviour is similar to SSiC.     

Evaluation of erosive wear resistance of TiN coatings by a slurry jet impact test

In this paper, it is proposed to use a new type of solid particle impact test (slurry jet) to swiftly evaluate wear properties of thin, single layered or multilayered coatings. By the slurry jet, 1.2 μm alumina particles were impacted at high velocity perpendicular to thin PVD coatings of TiN deposited on high speed steel substrate materials under various substrate temperatures. Since the coatings have a much higher wear resistance than the substrate material, the wear rate increases significantly to the higher level of the HSS material when the coatings are penetrated. This is utilized in the quantification of the assessment of coating wear. A ranking of wear resistance and correlations to the coating surface hardness measured by nano-indentation tests, and coating morphology and structures are given and discussed. The TiN deposited under the highest substrate temperature proved to have the highest wear resistance although it had a relatively low hardness. The wear rate of the TiN coatings varies with the orientation of grains, that is, the {1 1 1} orientation that dominates for the high temperature deposition shows a higher wear resistance than the {1 0 0} orientation, which corresponds with the cleavage fracture behavior. Thus, it can be recommended as a screening test when evaluating coatings and coated materials.     

重介系统管路中平板闸阀耐磨材料的选择

论述了耐磨材料的选用原则，介绍了常用耐磨材料性能，分析了阀门耐磨件材料经济性。     

Investigation of abrasive wear resistance and wear mechanism of composite alloys

The abrasive wear resistance of composite alloys comprising hard tungsten carbide and soft CuNiMn matrix under different wear conditions has been investigated and compared with CrMo cast iron. It was found that Yz-composite alloy with hard cast angular tungsten carbide has greater wear resistance than CrMo cast iron under two-body wear conditions, but lower resistance than Cr-Mo cast iron under three-body wear conditions. It was found that under three-body wear conditions selective wear of the matrix and digging or fragmentation of tungsten carbide particles dominate in Yz-composite alloy, and microcutting and deformed ploughing is dominant under two-body wear conditions. The abrasive wear resistance of composite alloys under two-body wear condition is independent of bulk hardness, but is closely related to the microhardness of tungsten carbide.     

Dimensional analysis for abrasive wear behaviour of various polyamides

Abrasive wear behaviour of a series of polyamides (PAs) with different methylene to amide ratio (CH₂/CONH) was analysed using Buckinghams dimensional analysis method and efforts for quantifying the contribution of the material properties towards the abrasive wear performance were also made. In order to calculate the wear coefficient (K), the data based on the experimental wear volume, operating parameters and the material properties were fitted into the non-linear wear equation. The non-linear wear equation was derived based on pi theorem using the dimensional analysis technique. The wear coefficient K decreased as load and abrasive grit size were increased. The theoretical and experimental wear volume correlated well in most of the cases. Among the selected material properties, the fracture stress (_*) and the critical crack length (C_*) were found to be the most important parameters, which controlled the abrasive wear behaviour of PAs.     

Origins of the friction and wear properties of antiwear additives

Experimental techniques have been developed to measure the friction, antiwear film‐forming and wear properties of lubricants in rolling–sliding contact. Friction measurements show that zinc dialkyldithiophosphates (ZDDPs) and also some other phosphorus‐based additives increase friction in mixed lubrication. Film thickness measurements show that this increase in friction correlates with the thickness of antiwear film. They also reveal some of the drivers of antiwear film formation and removal. A novel wear tester is described which enables the mild wear resulting from ZDDP‐containing oils to be monitored. Copyright © 2006 John Wiley & Sons, Ltd.     

Development of a new type micro slurry‐jet erosion (MSE) tester for evaluation of wear properties of hard thin coatings

Versatile and reliable techniques for evaluation of hard thin coatings are necessary for the development and tribological assessment of new coatings. We have proposed a new type of micro slurry‐jet erosion (MSE) test, i.e. a solid particle impact erosion test for swift evaluation of wear properties of hard thin coatings. We are using a new type of MSE test apparatus (pot type tester) that makes it possible to obtain the wear loss per unit mass of erodent, which in this test was alumina particles with an average size of 1.2 µm. Its performance was evaluated by using a Si wafer plate under various test condition. In addition, the MSE tester was demonstrated by evaluating the wear resistance of TiN on high‐speed steel substrate. The new MSE test generates highly reproducible results and is very sensitive to the quality of the coatings. Copyright © 2009 John Wiley & Sons, Ltd.     

Slurry abrasion response of surface engineered Ti6Al4VELI

Titanium alloys, by virtue of their outstanding combination of properties, continue to evolve as direct replacements for steels in offshore production systems to meet the challenging offshore application conditions. However, the wider use of titanium and its alloys is frequently retarded by their reputation for poor tribological behaviour. It is because of this simple engineering scenario that comparative tribological behaviour of surface engineered Ti6Al4VELI in abrasive slurry has been evaluated to identify treatments capable of improving its wear behaviour. To best simulate potential application conditions, sliding wear tests were carried out using a block-on-wheel test configuration in abrasive mud slurry. The wear volumes lost from the surface engineered Ti6Al4VELI test blocks ranged from negligibly small for substrates plasma sprayed with either WC–Co, Ni–Cr or Mo, to approximately twice that measured for a steel test block in the cases of untreated, shot peened, electroless Ni plated and anodised Ti6Al4VELI. Hard chrome plated material and thermochemically treated material demonstrated a certain degree of wear, which however, was significantly less than that found for the steel block.     

690合金材料的微动磨损特性研究

利用微动磨损试验机,在载荷50N以及位移幅值为60μm、100μm、150μm的工况下,研究了690合金材料在常温下的微动磨损行为及其动力学特性,采用激光共焦扫描显微镜(LCSM)和扫描电子显微镜(SEM)观察磨痕微观形貌。结果表明,载荷和位移幅值对微动特征有很大的影响,微动运行完全处于滑移状态。在滑移区,滑移磨损严重、磨痕面积大。690合金材料的磨损机制主要表现为磨粒磨损与剥层的共同作用。     

Relationship between wear of friction materials and dissipated power density

Specific tribometric tests showed both the effect and relevance of the power dissipated by friction upon the transition from mild wear to severe wear for friction materials. The dissipated power density could be viewed as an important variable either to identify the critical wear characteristics of friction materials or to make comparisons among different types of friction materials. The scanning electron microscopy analysis showed some correspondence between the sliding surface morphology after the friction tests and the wear rate obtained. Moreover, the phenomena observed are related to known mechanochemical wear mechanisms.     

Characterization of wear protective coatings

Arising from the necessity and the suitableness of wear protection by coatings, common coating techniques and treatment procedures are presented in a survey. For evaluation of the effectiveness of these anti-wear coatings a testing process was proposed consisting of three parts: (1) a test procedure to simulate the basic wear mechanisms; (2) investigations of the tribologically relevant material properties; (3) an integral wear test procedure. Taking thermal sprayed coatings and electrolytic depositions as examples, the characterization procedure is explained. The test systems designed at the Technical University Chemnitz-Zwickau for simulation of the basic mechanisms of adhesive and abrasive wear and long-term fatigue-wear are described with regard to the functional principle, the structure and the parameters to be ascertained.     

A review of the performance of engineering materials under prevalent tribological and wear situations in South African industries

The wear of materials used on machinery operating in a wide range of industrial situations such as mining, energy production and agriculture can cause serious inefficiencies, sudden breakdowns and consequential financial losses. Our work over two decades has concerned industrial problems encountered in South African industry, and laboratory simulations of abrasion, abrasion plus corrosion, adhesive wear, impact wear, cavitation, solid particle erosion and erosion plus corrosion situations have been successfully undertaken. Materials investigated include plain carbon and alloy steel, stainless steels, aluminium alloys, cast irons, tungsten carbide cermets, ceramics, polymers, composites and various surface treated and coated materials. The paper reviews the investigations carried out in our laboratories and conclusions we have made.     

轮轨磨损的试验研究

通过要用赫兹试验模拟的方法,在JD－1轮轨模拟试验机上进行了车轮轮对与钢轨磨损的试验研究。根据试验结果,指出蠕滑率,轴重以及总的循环次数是影响轮轨磨损的主要因素。     

Slurry wear behavior of zinc-based alloys: influence of some material and test parameters

This investigation pertains to the analysis of slurry wear behavior of a zinc-based alloy. The effects of material composition/microstructure, slurry composition and traversal distance and speed on the response of the alloy system have been studied. Sample rotation method was adopted for testing the samples. In some cases, unexpected wear response (from conventional understanding) was observed. For example, presence of a less corroding phase like Si particles in the alloy system caused inferior wear response while increasing traversal speed led to improved wear behavior (in the liquid-only medium). Further, hard sand particles suspended in the test environment offered superior wear characteristics despite their additional erosive and abrasive damage to the samples. In the tested range (20–60 wt%) of sand concentrations in the slurry medium, the wear rate increased initially with increasing sand concentration, attained the maximum (although less than the liquid-only medium) at 40% sand and then finally followed a reversal in the trend at a still higher sand concentration of 60%. Increasing traversal speed from 4.71 to 7.02 m/s led to inferior response while the silicon containing alloy performed better than the one without the element in general in liquid plus sand slurries. The wear rate increased with traversal distance initially, attained the maximum and then decreased once again at still larger distances. The sensitivity of the rate of increase/decrease in wear rate with distance became less in the presence of suspended sand particles in the medium (electrolyte). The observed wear response of the samples has been substantiated through specific characteristics of affected surfaces. The latter also helped to understand the operating material removal mechanisms.