Micro-abrasion mechanisms of cast CoCrMo in simulated body fluids

The abrasion seen on some of the retrieved CoCrMo hip joints has been reported to be caused by entrained hard particles in vivo. However, little work has been reported on the abrasion mechanisms of CoCrMo alloy in simulated body environments. Therefore, this study covers the mapping of micro-abrasion wear mechanisms of cast CoCrMo induced by third body hard particles under a wide range of abrasive test conditions. This study has a specific focus on covering the possible in vivo wear modes seen on metal-on-metal (MoM) surfaces. Nano-indentation and nano-scratch tests were also employed to further investigate the secondary wear mechanisms—nano-scale material deformation that involved in micro-abrasion processes. This work addresses the potential detrimental effects of third body hard particles in vivo such as increased wear rates (debris generation) and corrosion (metal-ion release). The abrasive wear mechanisms of cast CoCrMo have been investigated under various wear-corrosion conditions employing two abrasives, SiC (4 μm) and Al₂O₃ (1 μm), in two test solutions, 0.9% NaCl and 25% bovine serum. The specific wear rates, wear mechanisms and transitions between mechanisms are discussed in terms of the abrasive size, volume fraction and the test solutions deployed. The work shows that at high abrasive volume fractions, the presence of protein enhanced the wear loss due to the enhanced particle entrainment, whereas at much lower abrasive volume fractions, protein reduced the wear loss by acting as a boundary lubricant or rolling elements which reduced the abrasivity (load per particle) of the abrasive particles. The abrasive wear rate and wear mechanisms of the CoCrMo are dependent on the nature of the third body abrasives, their entrainment into the contact and the presence of the proteins.     

模拟体液环境下TAMZ合金的微磨粒磨损行为研究

采用TE66试验机对新型TAMZ钛合金的微磨粒磨损行为进行了研究.系统地考察了载荷、料浆浓度等因素对磨损率和摩擦因数的影响,建立了磨损机制图,并分析了磨损与腐蚀的协同作用.研究表明:在不同滑移距离时,TAMZ钛合金的磨损率均随载荷增加先减小后增大,随着料浆浓度的增加而增大.摩擦因数随着载荷增加呈现增大趋势,且在蒸馏水中摩擦因数的变化比在Hank's模拟体液中平稳.当料浆浓度较低时,磨损机制为二体磨损机制;随着料浆浓度增加、载荷增大,磨损机制向混合磨损和三体磨损转变.随着载荷增加,腐蚀与磨损的交互作用增强,而在交互作用中,微磨损所起的作用比腐蚀所起的作用要大.     

Micro-abrasion resistance of thermochemically treated steels in aqueous solutions: Mechanisms, maps, materials selection

The area of micro-abrasion is an interesting and relatively recent area in tribo-testing methodologies, where small particles of less than 10 μm are employed between interacting surfaces. It is topical for a number of reasons; its direct relation to the mechanisms of the wear process in bio-tribological applications, ease in conducting tests and the good repeatability of the test results. It has widespread applications in conditions used in the space and offshore industries to bio-engineering for artificial joints and implants.There have been many recent studies on the micro-abrasion performance of materials, ranging from work basic metals to nano-structured coatings. However, no significant work is reported on the micro-abrasion resistance of thermochemically treated steels. Hence, this paper looks at the performance of two thermochemically treated steels, Tenifer bath nitride stainless steel (T-SS) and vanadized carbon steel (V-CS) in such conditions with reference to the stainless steel (SS) by varying the applied load and sliding distance.The results indicated that T-SS demonstrates exceptionally poor resistance to micro-abrasion. It was observed that the heat treatment process and properties of the hardened layer (hardness and thickness) are extremely important in determining the micro-abrasion resistance of such steels. Finally, the results were used to develop micro-abrasion mechanism and wastage maps, which can be used to optimize the surface treated materials for micro-abrasion resistance.     

热压烧结氧化锆陶瓷的微磨料磨损机制研究

采用真空热压烧结工艺,在1 600 ℃下制备了含5%Y2O3稳定剂的氧化锆陶瓷.运用SEM、XRD等手段研究了氧化锆陶瓷的组织结构、性能,并研究了微磨料磨损条件下氧化锆陶瓷的摩擦磨损性能.结果表明:氧化锆具有良好的耐磨料磨损性能,微磨料磨损条件下,其磨损机制主要以微犁削和塑性变形为主.     

Dry-sliding self-lubricating ceramics: CuO doped 3Y-TZP

Dense 8 mol% CuO doped 3Y-TZP ceramics prepared by pressureless sintering at 1500 °C exhibits a good wear-resistance (specific wear rate k < 10⁻⁶ mm³ N⁻¹ m⁻¹) and promisingly low friction (coefficient of friction f = 0.2–0.3) when sliding against an alumina ball under unlubricated conditions. It was recognized that a self-lubricating mechanism is the most important contribution to the reduction of friction. During operation of the tribosystem, a soft interfacial patchy layer is generated in the contact area. As confirmed by calculations, based on a deterministic friction model, this soft interfacial patchy layer reduces friction. It was demonstrated that the presence of copper oxide is important for the formation of such an interfacial layer. The mechanism of the transition from mild to severe wear was also investigated. Detachment of a top layer in the wear track was proven to be the main reason for this tribological change.     

Y-TZP/板状氧化铝复相陶瓷的低温时效行为

通过X射线衍射仪和扫描电子显微镜研究了Y-TZP/板状氧化铝复相陶瓷在氢氧化钠碱性溶液中的低温(60～120℃)时效行为,并对时效后的复相陶瓷进行了抗弯强度和断裂韧度测试.结果表明:在时效过程中该复相陶瓷表面发生了氧化锆从四方相向单斜相的转变;相转变量随着时效温度和溶液pH值的升高而增加;时效使该复相陶瓷的抗弯强度略有下降,但是其断裂韧度基本保持不变.     

3Y-TZP陶瓷在水润滑条件下磨损特性的研究

采用销-盘式摩擦磨损试验机在水润滑条件下对3Y—TZP／（Mg,Y）-PSZ陶瓷摩擦副的磨损性能进行了试验研究。结果表明,3Y—TZP陶瓷的磨损率随着载荷和滑行速度的增加而增大。在低载低速下3Y—TZP陶瓷发生的是微量磨损,其磨损过程相当于抛光;随着载荷与滑动速度的增加,发生的是轻微磨损,相应的磨损机制为塑性变形和微犁削。在高载荷条件下发生了严重磨损,磨损的主要机制是表面断裂。     

Y-TZP陶瓷的去除机理及耐磨性研究进展

叙述了近年来Y-TZP陶瓷磨削去除机理、耐磨性的研究进展以及一些因素(如力学性能、显微结构、相变、摩擦介质等)对Y-TZP陶瓷耐磨性的影响。Y-TZP在磨削加工过程中主要通过塑性变形、脆性断裂和粉末化等方式去除;在摩擦磨损过程中主要的磨损机理是裂纹扩展、层离、剥落、晶粒拔出、犁耕、塑性变形等。二者的主要去除机理具有许多相似之处。     

Y-TZP/氧化铝(板晶)复相陶瓷的砂浆冲蚀磨损

以带有玻璃涂层的氧化铝微粉、小尺寸板晶(样板晶)和钇稳定四方氧化锆(3Y-TZP)微粉为原料,在常压下通过样板晶生长制备了氧化铝板晶体积分数为50%的Y-TZP/氧化铝(板晶)复相陶瓷。采用砂浆喷射装置,砂浆流速为10~40 m/s,冲击角为90°~15°,对比研究了该复相陶瓷和3Y-TZP陶瓷的砂浆冲蚀磨损。结果表明,2种材料的磨损率在75°~60°之间均出现最大值。磨损率大小受到材料自身硬度的影响,磨损率值随着砂浆流速的增加而增加。     

碳包纳米3Y-TZP陶瓷粉体的研究

采用CVD法制备碳包纳米3Y-TZP粉体,并经1200℃低温烧结获得3Y-TZP陶瓷体。分别通过XRD、HRTEM、SEM对碳包裹氧化锆粉体和烧成样品进行表征。结果表明,经过表面包碳修饰,获得了具有较好晶型结构,颗粒尺寸细小的碳包3Y-TZP粉体;与未包碳的试样相比,碳包裹层的存在有效抑制了烧结过程中氧化锆晶粒的长大。     

基于PLC的茶叶揉捻机自动上下茶系统设计

针对茶叶揉捻过程中出现的自动化程度不高,误差偏大等问题,以贵州某公司生产的绿宝石茶为对象,设计改进茶叶揉捻环节的上下茶系统。该系统分为上茶系统和下茶系统,主要控制单元由皮带秤、PLC和气缸组成。以西门子S7-300PLC为核心控制器,通过step7 V5.4软件编程控制,并通过Win CC flexible软件编辑人机界面,实现生产过程的触摸屏监控。该系统可以代替人工操作进行全自动上下茶操作,实现了茶叶揉捻环节的自动化流水作业。     

基于光谱反射率的茶染宣纸茶水浓度预测

茶染作为植物染色的一大门类,同时具有良好的环保性能和深厚的文化底蕴。为了能够准确描述茶叶染色的光谱变化,本文研究茶染后宣纸的光谱反射率与茶叶浓度的关系。首先采用分光光度计测量400～700 nm波段被茶叶染色后宣纸的光谱反射率,分别基于偏最小二乘回归模型、BP神经网络和连续投影算法(SPA)选择特征波段建立光谱信息与茶叶浓度之间关系的预测模型。然后以光谱反射率作为输入变量,对茶叶浓度进行预测。结果表明：基于偏最小二乘法、BP神经网络和连续投影算法 选择特征波段建立模型,通过茶染宣纸的光谱反射率来预测茶叶浓度具有较高的稳健性和可信度,其中SPA-BP神经网络模型的效果最优,平均预测正确率为98.40%,决定系数为0.9910,均方根误差为0.8433。这说明通过茶染宣纸的光谱数据来预测茶叶浓度具有可行性。     

一种基于茶艺功能的新型自动控制泡茶机

针对现有泡茶机设计时没有整体考虑合适的茶水混合比例、泡茶水温、冲泡时间、冲泡次数而不利于保证茶汤感官品质的不足,设计了一种自动控制茶艺泡茶机。通过采用机械伺服系统、温度传感器、继电器和控制芯片,实现了对红茶、绿茶和花茶等不同茶种的泡制方法和工艺的自动控制。研究结果表明,该产品是一种高品质的自动控制茶艺型泡茶工具。     

荧光光谱检测技术在茶饮料成分分析中的应用

荧光光谱检测技术已广泛用于有机物的定性和定量分析,取得了良好的效果.本文介绍了荧光光谱法的检测原理和检测系统的组成.采用该荧光检测系统在激发波长300～550nm、发射波长310～710nm处检测了茶饮料的荧光光谱,通过对荧光光谱的分析,建立了主要成分的荧光光谱特征数据库.该方法有助于解决市场上真假茶饮料的质量鉴别问题.     

显微结构对Y-TZP/Al2O3复合陶瓷磨料磨损性能的影响

以不同Y2O3加入方式(如化学共沉淀和机械混合)制备的Al2O3增强Y-TZP陶瓷(AZD)为研究对象，研究了显微结构对陶瓷耐磨性的影响。结果表明：化学共沉淀法制备的CYADZ与机械混合的MYADZ的硬度和断裂韧性值相近：CYADZ结构均匀、品粒细小，而由于Y2O3的不均分布，MYADZ结构不均、晶粒相差较大。球磨磨料磨损后，CYADZ复合陶瓷较MYADZ复合陶瓷耐磨性好，宏观力学性能如硬度和断裂韧性对陶瓷材料耐磨性的影响应以显微结构为先决条件。     

TiC／（Al2O3／Y-TZP）纳微米复合陶瓷材料的性能及显微结构研究

采用热压烧结制备了TiC/(Al2O3/Y-TZP)纳微米复合材料,用SEM观察了复合材料断口形貌和微观结构,研究了纳米TiC含量对复合材料的力学性能的影响,结果表明:20%TiC(15%Al2O3/5Y-TZP)复相陶瓷抗弯强度和断裂韧性高达620MPa、6.8MPa·m1/2.     

磨粒对ADZ复合陶瓷材料磨损性能的影响

采用块 -块摩擦磨损试验机在不同磨粒的 5 %NaOH泥浆中 ,对氧化铝增强四方氧化锆多晶陶瓷材料 (ADZ)的磨损性能进行了研究。研究结果表明尖锐磨粒对ADZ复合陶瓷材料磨损的影响要比球形磨粒严重的多 ,磨料硬度是影响陶瓷材料磨损率的重要因素 ,磨损率随磨粒硬度的提高而增大。在不同形状的SiO2 磨粒的泥浆中ADZ陶瓷材料的主要磨损机理为塑性变形和微犁削。在高硬度Al2 O3磨料的泥浆中ADZ陶瓷材料磨损表面以断裂机制占主导地位。     

商南茶叶中微量硒的提取与测定

采用正交设计[L16（45）]试验,研究了茶叶中微量硒的提取和测定条件。在此基础上建立了铁氰化钾-盐酸存在下用微波消解-流动注射-氢化物发生-原子荧光光度法测定茶叶中微量硒的新方法。该方法的回归方程为y=62.91x-0.3529,R=0.9996,线性范围为0～20μg/L,检出限为0.01μg/L,相对标准偏差为2.7%（n=11）。用此方法测定了5种商南茶叶中的微量硒,回收率96.5%～103.4%,相对标准偏差2.9%～4.1%（n=7）,结果令人满意。     

Modeling of thermal processes in the tea withering chamber

An analysis of the temperature distribution in the tea-withering chamber has been carried out based on mathematical modeling. The revealed non-uniformity of the temperature distribution was adjusted due to the use of additional heat sources. The novelty of the work consists of applying additional heat sources in the areas where the conveyor belt that represents the modern energy-efficient elastic electric heaters are located.     

火焰原子吸收光谱法测定茶叶中铅铜

本文采用干灰化 盐酸消解试样 ,消解液用火焰原子吸收光谱法测定茶叶中铅和铜。在铅吸收波长 2 1 7 0nm处 ,铅在 0～ 1 0 μg/mL呈现良好的线性关系 ,在铜吸收波长32 4 nm处 ,铜的线性范围为 0～ 5 0 μg/mL ,相关系数γ =0 .9996。以 3SA/S计 ,铅检出限 :0 0 6 μg/mL ;铜检出限 :0 0 0 8μg/mL ;方法精密度RSB <3%。回收率 96 %～ 1 0 2 %。