天然牙釉质/纯钛摩擦磨损行为的研究

对天然牙釉质与TA2纯钛球组成的摩擦副进行了实验研究，结合显微分析，研究了牙釉质的摩擦磨损行为。结果表明牙冠外层釉质的摩擦学特性与釉质的基本结构釉柱的排列方向密切相关，釉质在He面上的耐磨性明显优于垂直方向。     

牙本质层对人牙力学性能的影响研究

牙釉质位于牙冠的外层,是人体内的最硬组织,具有优异的力学性能和耐磨性;相比牙釉质,内层的牙本质含有较多的有机物,具有较高的韧性。采用显微硬度仪和激光共聚焦扫描显微镜,研究牙本质层去除前后牙釉质的表面硬度和断裂韧性,分析牙本质层对人牙力学性能和耐磨性的影响。结果表明,牙本质层的存在对外层牙釉质的维氏硬度值无显著影响,但一旦去除牙本质层,牙釉质表面断裂韧性降低,载荷越大,断裂韧性降低越明显。可见,牙齿的力学性能与其独特的微观结构密切相关,牙冠内层硬度较低的牙本质的存在能提高牙齿抵抗脆性破坏的能力。     

牙本质层对人牙力学性能的影响

牙釉质位于牙冠的外层,是人体内的最硬组织,具有优异的力学性能和耐磨性;相比牙釉质,内层的牙本质含有较多的有机物,具有较高的韧性。采用显微硬度仪和激光共聚焦扫描显微镜,研究牙本质层去除前后牙釉质的表面硬度和断裂韧性,分析牙本质层对人牙力学性能和耐磨性的影响。结果表明,牙本质层的存在对外层牙釉质的维氏硬度值无显著影响,但一旦去除牙本质层,牙釉质表面断裂韧性降低,载荷越大,断裂韧性降低越明显。可见,牙齿的力学性能与其独特的微观结构密切相关,牙冠内层硬度较低的牙本质的存在能提高牙齿抵抗脆性破坏的能力。     

关于我国摩擦学发展战略的初步思考

简要回顾了40年来摩擦学的发展历程,综述了近两年来摩擦学研究的最新进展和发展趋势以及英国摩擦学研究的现状。在此基础上,分析了摩擦学面临的挑战,并初步提出了我国摩擦学的发展战略。     

摩擦学尺寸效应及相关问题的思考

根据文献研究,简单阐述了尺寸效应的研究现状、宏观/微观摩擦学的差异。从尺寸大小的角度,提出了应当对摩擦学传统理论有效性、过渡状态摩擦学、摩擦系数、摩擦学与材料、系统结构和物理规律尺寸效应与摩擦学特性的关系等一些摩擦学领域的重要基础问题进行认真思考和系统研究。     

摩擦学系统结构寻优模型研究

通过对摩擦学系统条件转化的研究和转化实例的分析,提出了解决摩擦学系统结构寻优问题的新思路和模型。经摩擦学验证试验得出结论：利用人工智能技术可以基本实现摩擦学系统结构条件下的摩擦学特性转化。对转化结果求最小值。可得该摩擦学系统条件的最优解。摩擦学设计用户和专业摩擦学研究人员可以由此优化方法完成对摩擦学试验研究方案的优化和摩擦学设计参数的正确选择。     

当前国际摩擦学发展的某些新动向

本文论述了当前国际摩擦学发展的某些新动向，指出：表面工程的研究是当前摩擦学的重点领域，摩擦学系统工况监测及故障诊断新技术迅速崛起；磁记录系统摩擦学研究是微摩擦学领域的热门课题；陶瓷摩擦学研究是当前国际摩擦学研究的前沿课题之一。     

摩擦学在四川的发展应用

1979年全国第二届摩擦学学术会议之后,摩擦学在四川得到较大发展。一方面以高等院校,研究机关为主的研究人员在摩擦学原理,测试方法,新材料研究上,取得一批可喜成果,并在实际应用中得到验证;另一方面是工业企业中从事摩擦学活动的科技工作者在采用摩擦学原理和技术于生产实践中,取得了明显的经济效益。本文从摩擦学学会活动的角度介绍了五年来摩擦学在四川的发展情况。     

世纪回顾与展望——摩擦学研究的发展趋势

在回顾摩擦学发展历史的基础上,总结20世纪60年代以来,在摩擦学主要研究领域包括流体润滑、材料磨损与表面处理技术、纳米摩擦学等的发展现状和展望。分析了相关学科的发展和学科交叉对摩擦学研究的推动作用,并介绍了摩擦学与其他学科交叉领域如摩擦化学、生物摩擦学、生态摩擦学和微机械学等的发展概况和趋势。     

齿轮摩擦学的研究及展望

文中阐述了齿轮摩擦学研究工作的特点,说明齿轮摩擦学是一门跨学科的新兴学种、它是摩擦学基本原理在齿轮上的应用。作者对齿轮摩擦学的研究内容谈了自己的体会和看法。最后,对于如何搞好齿轮摩擦学的应用研究和成果推广问题提出了建议。     

Hardness,friction and wear studies on hydrogen peroxide treated bovine teeth

A possible problem with peroxide based tooth whitening is the loss of tooth hardness and higher susceptibility to enamel surface wear. This study focussed on the effects of acidic and neutral hydrogen peroxide solutions (6 and 30% w/v) on hardness, friction and wear of bovine enamel. The experiments showed that treatments with neutral peroxide reduced wear and the loss of enamel hardness up to 2–3 times. In addition, further investigation on remineralisation with amorphous calcium phosphate showed an increase in hardness after treatment. Friction coefficients of teeth against steel varied between 0.25 and 0.7, and wear coefficients ranged between ≈10⁻⁶ and 10⁻⁷ mm³/N m. From this study, it is possible to explain the wear behaviour of HP treated enamel with changes in hardness.     

On evaluation of wear resistance of tooth enamel and dental materials

A survey of the literature shows that in many studies on the wear resistance of tooth enamel or dental materials a large scatter of experimental data has been obtained when wear tests were performed at a fixed load. Despite the steady loading, wear conditions vary during sliding, since tooth enamel as well as dental materials have inhomogeneous structure. This leads to changes in contact interactions between sliding surfaces, and as a result, we get changes in the friction and wear behaviour of tested materials. This is why at the same loading the wear can be different. In this study, more reliable approach to evaluation of the wear resistance of human enamel and dental materials is proposed. The procedure is based on the correlation between the volumetric wear and the friction energy dissipated during sliding. The model can be useful to compare the wear resistance of different dental materials tested in different ambient conditions.     

激光处理对人牙釉质酸蚀和耐磨性能的影响

以人牙釉质为研究对象,对牙釉质表面进行激光处理,对激光处理前后牙釉质的表面形貌、力学性能和耐磨性能进行分析,旨在探索激光处理对牙齿酸蚀的抑制和修复作用,为激光在牙齿酸蚀抑制方面的临床应用提供理论指导。结果表明,原始牙釉质表面和酸蚀牙釉质表面经激光处理后,其表面硬度均显著提高、抗酸蚀能力增强;但是,激光处理会导致牙釉质表面变得粗糙,出现大量裂纹和孔洞,牙齿表面的弹性模量降低,表面脆性增大,从而使得牙齿耐磨性显著降低,造成的损伤重于酸蚀。     

Study of <Emphasis Type="Italic">in vitro</Emphasis> wear of human tooth enamel

Wear behavior of human tooth enamel against titanium alloy has been investigated under the lubrication of artificial saliva, using a reciprocating sliding wear test machine with a normal load of 20 N, a reciprocating amplitude of 500 μm, and a frequency of 2 Hz. Tests lasting up to 10, 100, 1000, 2000, and 5000 cycles were conducted, respectively. The worn surface of enamel after different cycles was analyzed by means of various microscopic examinations. The results showed that, a delamination mechanism occurred on the surface of enamel at the early stage of wear. The wear rapidly increased in depth with the number of cycles. As the wear proceeded, the surface of enamel was gradually covered with a wear particle layer, and the wear rate decreased. Finally the wear of enamel stayed stable. Microscopic examinations indicated that the wear of enamel was controlled by the mechanical removal of materials without obvious changes in the compositions and crystal structures of the enamel. The enamel rods were worn away after the inter-rod enamel.     

Variations in the properties of the friction zone of metallic composites under the effect of electric current and Pb-Sn melt in the contact gap

The paper deals with study of the wear rate and specific surface electric resistance of the contact of metallic composites in dry friction at a high current density. Friction induced structures are shown to appear in the surface layer of the composites. The specific electric resistance of the friction induced structures is estimated quantitatively. It is found that their specific electric resistance is similar to that of the known electrographites and carbon graphites, resulting in a high contact resistance. The electric resistance and wear rate of the friction zone are diminished by the introduction of a Pb-Sn melt. The possibility of developing of an efficient sliding electric contact of two metallic composites with a metal melt between their friction surfaces is noted.     

人牙釉质的磨损机制研究

以钛合金为对摩材料,考察了人牙釉质在人工唾液介质中的滑动磨损进程,结合微观分析,研究了牙釉质的磨损机制。结果表明:在摩擦过程中,随着釉质表面发生脆性剥落,磨损从两体接触磨损转变为三体磨粒磨损,磨损加剧;随着接触时间增长,硬质磨屑尺寸变小,磨损率降低,进入稳定磨损阶段。牙釉质磨损为机械磨损过程,釉质表面基本无摩擦化学作用。     

激光熔覆合金表面耐磨性试验研究

使用CO2激光器对45#钢表面进行Co基和Ni基合金熔覆处理。利用销盘式摩擦试验机对激光熔覆表面进行摩擦磨损试验,研究干摩擦和润滑条件下磨损机理。Ni合金熔覆层比Co基耐磨性要好。润滑条件下,两种合金的耐磨性比干摩擦都得到很大提高。     

Unique dentition of lungfish

Lungfish are a group of ancient fish, represented almost continuously in the fossil record from their first appearance in the Devonian to the present time. They have numerous unique characters in the dentition, found only among lungfish, as well as some that are shared with other groups of fish and with higher vertebrates, such as a thin layer of true enamel, instead of the enameloid found in the dentition of most fish. Unique characters include the diversity of forms of dentine in the tooth plates, as well as the organisation of the dentines and the unusual mode of continuous growth of the dentition. Their enamel is based on amelogenin formed by the ameloblasts of the dental lamina, and is mineralised by long crystals of calcium hydroxyapatite deposited in layers over the developing tooth. The different forms of dentine, which show progressive evolutionary change within the group, are based on an extracellular matrix of collagen, mineralised with calcium hydroxapatite of variable crystalline form. Cells that line the oral cavity produce the ameloblasts that are endodermal in origin, and cells that form the dental papillae are, like the other cells that secrete skeletal tissues, derived from head mesoderm, as in other vertebrates. Unique to all dipnoans is the fusion of the dental tissues to the underlying bone and the way in which bone, included within the tooth plate, remodels to permit growth in the whole dentition.     

Friction and wear behavior of human teeth under various wear conditions

Previous reports have described the differences in the friction and wear behavior between different zones of human teeth. The objective of this research was to study the friction and wear behavior of human teeth under different wear conditions to extend the understanding of the tooth wear process, as well as to provide a more rational explanation for wear mechanism of teeth. Two typical wear tests, namely two- and three-body wear, were conducted on human tooth enamel using a reciprocating apparatus. The effect of food particles was of particular interest. Three loads, 10, 20 and 40 N, were used. Wear was assessed by sample wear volume. The results show that human tooth enamel exhibits lower friction and smaller wear volume under three-body wear conditions than under two-body wear conditions. Under three-body wear conditions, although increasing normal load results in a progressive increase in the wear volume of enamel, the increasing rate is lower at high load than that under two-body wear conditions. Further analysis of wear surfaces indicates that human tooth enamel experiences different wear mechanisms under different wear conditions.