人工关节材料的研究进展

高可靠性、耐磨人工关节材料的研究开发对人工关节的临床应用极为重要.简述了人工关节的分类,对Al2O3与ZrO2人工关节的研究现状、可靠性和耐磨机制进行了综述,对ZrO2的增韧机理和稳定剂CeO2进行了讨论,最后对Ce-TZP/Al2O3作为一种新的人工关节材料在临床上的应用进行了展望.     

State of the art of bioimplants manufacturing: part II

The manufacturing of bioimplants not only involves selecting proper biomaterials with satisfactory bulk physicochemical properties, but also requires special treatments on surface chemistry or topography to direct a desired host response. The lifespan of a bioimplant is also critically restricted by its surface properties. Therefore, developing proper surface treatment technologies has become one of the research focuses in biomedical engineering. This paper covers the recent progress of surface treatment of bioimplants from the aspects of coating and topography modification. Pros and cons of various technologies are discussed with the aim of providing the most suitable method to be applied for different biomedical products. Relevant techniques to evaluate wear, corrosion and other surface properties are also reviewed.The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-018-0218-9     

State of the art of bioimplants manufacturing: part I

Bioimplants are becoming increasingly important in the modern society due to the fact of an aging population and associated issues of osteoporosis and osteoarthritis. The manufacturing of bioimplants involves an understanding of both mechanical engineering and biomedical science to produce biocompatible products with adequate lifespans. A suitable selection of materials is the prerequisite for a long-term and reliable service of the bioimplants, which relies highly on the comprehensive understanding of the material properties. In this paper, most biomaterials used for bioimplants are reviewed. The typical manufacturing processes are discussed in order to provide a perspective on the development of manufacturing fundamentals and latest technologies. The review also contains a discussion on the current measurement and evaluation constraints of the finished bioimplant products. Potential future research areas are presented at the end of this paper. The full text can be downloaded at https://link.springer.com/article/10.1007/s40436-017-0207-4     

Solid lubricants: a review

The fundamental mechanisms of solid lubrication are reviewed with examples from well-known solid lubricants like the transition metal dichalcogenides and diamond-like carbon families of coatings. Solid lubricants are applied either as surface coatings or as fillers in self-lubricating composites. Tribological (friction and wear) contacts with solid lubricant coatings typically result in transfer of a thin layer of material from the surface of the coating to the counterface, commonly known as a transfer film or tribofilm. The wear surfaces can exhibit different chemistry, microstructure, and crystallographic texture from those of the bulk coating due to surface chemical reactions with the surrounding environment. As a result, solid lubricant coatings that give extremely low friction and long wear life in one environment can fail to do so in a different environment. Most solid lubricants exhibit non-Amontonian friction behavior with friction coefficients decreasing with increasing contact stress. The main mechanism responsible for low friction is typically governed by interfacial sliding between the worn coating and the transfer film. Strategies are discussed for the design of novel coating architectures to adapt to varying environments.     

Hüftgelenkersatz – eine tribologische und konstruktive Herausforderung

Artificial hip joints - a challange for ideasconcerning tribology and designing Artificial hip joints are successfully used since two decades. The artificial joint is set up out of a femoral ball head made of a cobalt chromium alloy or alumina ceramic. The ball head is mostly articulating against an acetabular cup made of polyethylene (UHMWPE). The polyethylene wear debris causes osteolysis. Because of the osteolysis the implants will loosen and a revision of the artificial hip joint has to be performed. The objective of all R & D projects is to minimize the polyethylene wear. The state-of-the-art is discussed. There are new materials and methods that offer oppertunities for new combinations. Possibilities, limitations and the successes are discussed. The clinical experience during the last two decades proved that femoral ball heads made of alumina ceramic could reduce the problems of osteolysis.     

颗粒增强金属基复合材料的干摩擦性能与磨损机理

颗粒增强金属基复合材料(PMMC5)具有优良的耐磨性，在摩擦磨损领域有着广阔的应用前景。本文评述了近年来关于PMMCs干摩擦磨损行为的研究结果，从材料因素和外部条件两个角度分析了各种因素对材料耐磨性、摩擦系数和配偶件磨损的影响，总结了不同条件下复合材料的磨损机制，并提出了设计摩擦磨损性能优良的PMMCs体系的可能途径。     

Wear of ultra-high molecular weight polyethylene against damaged and undamaged stainless steel and diamond-like carbon-coated counterfaces

The wear of ultra-high molecular weight polyethylene (UHMWPE) in artificial joints and the resulting wear debris-induced osteolysis remains a major clinical concern in the orthopaedic sector. Third-body damage of metallic femoral heads is often cited as a cause of accelerated polyethylene wear, and the use of ceramic femoral heads in the hip is gaining increasing favour. In the knee prostheses and for smaller diameter femoral heads, the application of hard surface coatings, such as diamond-like carbon, is receiving considerable attention. However, to date, there has been little or no investigation of the tribology of these coatings in simulated biological environments. In this study, diamond-like carbon (DLC) has been compared to stainless steel in its undamaged form and following simulated third-body damage. The wear of UHMWPE was found to be similar when sliding against undamaged DLC and stainless steel counterfaces. DLC was found to be much more damage resistant than DLC. Under test conditions that simulate third-body damage to the femoral head, the wear of UHMWPE was seven times lower against DLC than against stainless steel (P < 0.05). The study shows DLC has considerable potential as a femoral bearing surface in artificial joints.     

Comparison of the wear of aged and non-aged ultrahigh molecular weight polyethylene sterilized by gamma irradiation and by gas plasma

The wear of ultrahigh molecular weight polyethylene in artificial joints is a major cause of long-term osteolysis and loosening. The wear rate of aged and non-aged ultrahigh molecular weight polyethylene sterilized by both gamma irradiation in air and gas plasma has been studied in simple configuration wear tests. Fourier transform infrared analysis (FTIR) showed marked oxidative degradation of the irradiated and aged material compared to the gas plasma sterilized and aged material. The wear rate of the irradiated and aged material was significantly (three times) higher than the gas plasma sterilized, gas plasma sterilized and aged, and non-sterilized materials. Alternative sterilization procedures such as gas plasma, when used instead of gamma irradiation in air, are likely to reduce the incidence of long-term osteolysis.     

Wear studies on the likely performance of CFR-PEEK/CoCrMo for use as artificial joint bearing materials

It is well known that a reduction in the volume of wear produced by articulating surfaces in artificial joints is likely to result in a lower incidence of failure due to wear particle induced osteolysis. Therefore, new materials have been introduced in an effort to produce bearing surfaces with lower, more biologically acceptable wear. Polyetheretherketone (PEEK-OPTIMA) has been successfully used in a number of implant applications due to its combination of mechanical strength and biocompatibility. Pin-on-plate wear tests were performed on various combinations of PEEK-OPTIMA and carbon fibre reinforced PEEK-OPTIMA (CFR-PEEK) against various CoCrMo alloys to assess the potential of this material combination for use in orthopaedic implants. The PEEK/low carbon CoCrMo produced the highest wear. CFR-PEEK against high carbon or low carbon CoCrMo provided low wear factors. Pin-on-plate tests performed on ultra-high molecular weight polyethylene (UHMWPE) against CoCrMo (using comparable test conditions) have shown similar or higher wear than that found for CFR-PEEK/CoCrMo. This study gives confidence in the likelihood of this material combination performing well in orthopaedic applications.     

超高分子量聚乙烯人工关节研究进展

人工关节是替代病变或损伤关节的植入性假体,除了应满足生物相容性要求外,必须具有足够的耐磨损性能、力学性能和抗氧化性能等。超高分子量聚乙烯因其自身优良的理化性能而被广泛应用于人工关节置换用材料。但随着超高分子量聚乙烯人工植入体使用时间的延长会导致其不同形式的失效,如磨损引起的骨质溶解,给骨科患者生活带来不便。综述了国内外提高超高分子量聚乙烯人工关节植入体综合性能而对材料进行改性处理的各种方法,包括辐照交联、热处理、加入抗氧剂等。最后总结了通过调控流动场诱导形成自增强结构,来改善人工关节植入体力学性能的最新进展,并展望了超高分子量聚乙烯人工关节高性能化的未来研究方向。     

Microstructural evolution in lubricious ZnO films grown by pulsed laser deposition

Zinc oxide (ZnO) is well known to the electronic industry as a piezoelectric material. Recent research from this laboratory also indicates the potential of ZnO as a tribological material. The current work describes the evolution of microstructure with deposition parameters in pulsed laser deposited ZnO thin films, specifically targeted for friction and wear applications. Films were characterized by high resolution scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). Friction and wear measurements were made using a ball-on-disk tribometer. Films were grown in vacuum (V) as well as in 5 mTorr of oxygen (O₂), while the substrates were kept at room temperature (RT). The RT/V ZnO films have (002) columnar texture with an average column width of 20 nm. The RT/O₂ films also are nanoclumnar with (002) texture, but each column is a mosaic of low-angle boundaries. Deformation mechanisms associated with nanocrystalline grain structure were analyzed with particular reference to sliding contact. Mechanisms to provide the observed low friction of RT/O₂ films (μ=0.15–0.20) have been activated by its mosaic structure.     

Performance of sialon cutting tools when machining nickel-base aerospace alloys

Abstract

A range of sialon compositions have been used to machine the nickel-base alloy Incoloy 901. Wear measurements, taken throughout the machining tests, have shown that tool life and flank wear resistance increase with α-sialon content. An examination of the wear mechanisms involved suggests that this can be ascribed to the increased resistance to dissolution into the work piece, afforded by the higher aluminium and oxygen levels in α-sialon compared with those in β–sialon. At higher cutting speeds one of the main mechanisms of tool wear was rake face flaking, and resistance to this mechanism was found to increase with tool material grain size. A model has been proposed for the initiation and propagation of the cracks which produce this type of failure. At lower cutting speeds depth-of-cut notch wear was of major importance, and resistance to this mechanism was found to decrease with increasing grain size.

MST/249     

Experimental and mathematical modeling for fracture of rock joint with regular asperities

This paper is aimed at developing a mathematical model for the deformation behavior of a rock joint that explicitly accounts for the effects of joint surface topography. The present work is focused on rock joints with triangle-shaped regular asperities. Specimens of artificial rock joint with triangle-shaped asperities were made of simulated rock material and tested in the laboratory. Experimental results are examined to identify three mechanisms that influence the deformation of a rock joint: sliding, separation of asperity contact-faces, and shear fracture of asperities. A modeling methodology is then described and the behaviors of an asperity contact-face, including separation, sliding and shear fracture are discussed. The stress-deformation relationship of a rock joint is subsequently derived and the model performance is evaluated by comparing the predicted results from the derived model and the measured results from experiments.     

Biotribological properties of UHMWPE grafted with AA under lubrication as artificial joint

Osteolysis caused by wear particles from polyethylene in the artificial hip joints is a serious issue. In order to endow the low friction and wear of the bearing surface of ultra-high molecular weight polyethylene (UHMWPE) artificial joint for a longer term, hydrophilic acrylic acid (AA) was grafted on UHMWPE powders with the method of ultraviolet irradiation and then the modified powders were hot pressed. The tribological properties of modified UHMWPE sliding against CoCrMo metallic plate on reciprocating tribometer under calf serum, saline and distilled water lubrication during a long-term friction were investigated. The measurement of Fourier-transform infrared spectroscopy indicates that AA is successfully grafted on the surface of UHMWPE powders by photo-induced graft polymerization. Contact angles of UHMWPE are decreased from 83° to 35° by grafting and the surface wettability is effectively improved. The tensile strength of modified sample decreases. The friction coefficient and wear rate of UHMWPE-g-PAA under calf serum, saline and distilled water lubrication are lower than that of untreated UHMWPE. With the increase of grafting ratio, the wear rate of UHMWPE-g-PAA decreases firstly and then increases. The modified UHMWPE with grafting ratio of 3.5 % has the lowest wear rate, which is just quarter of the untreated UHMWPE. The hydrated PAA polymer brushes enclosed in the UHMWPE bulk material provide continuous lubrication during long term sliding.     

Diesel engine crankshaft journal bearings failures: Case study

Wear as a tribological process has major influence on the reliability and life of engine crankshaft bearings. The importance of field examinations of bearing failures due to wear is very well known. They point to the possible causes of wear and to the necessary treatment for its reduction or elimination. The paper presents the results obtained by examining 616 crankshaft bearings, damaged by different mechanisms. The bearings were installed in high-speed diesel engines, and were gathered for two years, during general repairs of the engines (overhaul), i.e. after 3000–5000 working hours. After the examination of the bearings, the fault tree analysis (FTA) was performed to determine the root causes for engine bearing failures. Each type of damage that was identified was illustrated with an appropriate high-resolution photograph. The investigations show that the basic and most conspicuous types of damage which cause bearing failures are abrasive, adhesive and surface fatigue wear. The paper also considers the effects of the place of installation and type of bearing material in respect to each type of wear.     

The wear behaviour of oxide ceramics-A Review

The paper reviews the wear behaviour of oxide ceramics. Wear maps are considered and consequently mild and severe wear are defined. Since the use of ceramics in engineering applications require operation in the mild wear regime, the paper concentrates on mild wear mechanisms, but also considers factors which control the transition to severe wear. Within the mild wear regime, the formation of tribofilms are discussed and the manner in which dislocation activity leads to the wear transition is considered. The wear of so-called ceramic nanocomposites, for which no time dependent wear transition has yet been observed, is considered and the reasons for enhanced performance discussed. The role of transformation toughening in zirconia ceramics is considered in detail, and reasons for the generally poor wear response of these materials defined.     

A review on particulate slurry erosive wear of industrial materials: In context with pipeline transportation of mineral−slurry

Pipeline transportation of slurry is being carried out all over the world. Slurry pipeline wear is one of the major problems associated with it. The wear rate of the slurry pipeline depends upon factors such as slurry properties, slurry particle properties, flow properties, and pipeline wall properties. Any change in these properties results in change in pipeline wear rate. There is a need to study the effect of individual properties, for predicting the slurry pipeline life span and also to find the methods to minimize the wear rate. In this review paper, an attempt has been made to discuss the parameters which are believed to be the primary factors that affect material wear rate. Several mechanisms and equations suggested by various researchers for the prediction of wear of materials are also reviewed. Most of the models incorporate the effects of only few parameters involved during the wear process. These equations are specific and valid up to limited operating conditions. No general equation have been evolved which can be used under any operating condition, with better accuracy. This can be attributed to lack of data at microscopic level and also to change in the wear mechanisms under various operating conditions.     

Effects of surface coating on reducing friction and wear of orthopaedic implants

Coatings such as diamond-like carbon (DLC) and titanium nitride (TiN) are employed in joint implants due to their excellent tribological properties. Recently, graphite-like carbon (GLC) and tantalum (Ta) have been proven to have good potential as coating as they possess mechanical properties similar to bones—high hardness and high flexibility. The purpose of this systematic literature review is to summarize the coating techniques of these four materials in order to compare their mechanical properties and tribological outcomes. Eighteen studies published between January 2000 and February 2013 have met the inclusion criteria for this review. Details of their fabrication parameters, material and mechanical properties along with the tribological outcomes, such as friction and wear rate, were identified and are presented in a systematic way. Although experiment conditions varied, we conclude that Ta has the lowest wear rate compared to DLC, GLC and TiN because it has a lower wear rate with high contact pressure as well as higher hardness to elasticity ratio. However, a further tribology test is needed in an environment which replicates artificial joints to confirm the acceptability of these findings.     

Investigation of microstructure and mechanical properties of aluminum hybrid nano-composites with the additions of solid lubricant

In this experimental study, the tribological behavior of Al 2024–5 wt.% SiC–X wt.% graphite (X = 5 and 10) hybrid nano-composites was produced using powder metallurgy (P/M) technique. All specimens were prepared by mechanical milling of Al 2024 and SiC–Gr nano-composite powders, followed by a blend–press–sinter methodology. Pin on disc type apparatus has been used for determining the wear loss. The sintered samples have been characterized by XRD. Wear mechanisms are discussed based on scanning electron microscopy observations of worn surface and wear debris morphology. The hardness and wear resistance of the hybrid nano-composites were increased considerably by increasing the reinforcement content. The nano-composite with 5 wt.% SiC and 10 wt.% Gr showed the greatest improvement in tribological performance. Primary wear mechanisms for hybrid nano-composites were determined to be formation of lubricating layer on the surface of samples. The overall results revealed that hybrid aluminium nano-composites can be considered as an outstanding material where high strength and wear-resistant components are of major importance, particularly structural applications in the aerospace, automotive and military industries.     

Texture formation in metal alloys with cubic crystal structures

The present paper gives a concise overview of a number of current issues in the literature on texture formation in alloys with cubic crystal structures, mainly steel and aluminium alloys. As crystallographic texture determines to a large extent the anisotropy of material properties, it is of paramount importance to understand and control the physical mechanisms by which the texture is formed in the subsequent stages of metals manufacturing processes. In the present overview three key solid-state transformation processes are considered: allotropic phase transformations, plastic deformation and recrystallisation. The intention is to highlight a number of key elements in the literature and some recent tendencies, which may provide some insight to scientists and engineers dealing with texture issues in daily practice.