电镀锡板表面抗划伤性的研究Ⅰ.关于测试方法

电镀锡板弧表面抗划伤性近来受到越来越多的重视,但至今对此尚无统一的标准测试方法。经过分析比较,移植两种简单有效的测试方法－涂膜铅笔硬度泮和涂膜划痕硬度法来测试和评价电镀锡板表面抗划伤性,试验结果表明该测试方法可以用来比较电镀锡板表面抗划伤性。     

PP复合材料耐刮擦性能的研究

通过多指刮擦试验机对聚丙烯(PP)及其复合材料进行了系统的刮擦实验测试,采用光学显微镜观察了材料的刮擦损伤形貌,以研究PP及其复合材料的耐刮擦性能及损伤机理;通过差示扫描量热仪(DSC)测试了材料的结晶度,研究了耐刮擦助剂和磷酸盐成核剂对材料力学性能、结晶性能和耐刮擦性能的影响,以探讨材料力学性能、结晶性能与耐刮擦性能之间的关系。     

Low-Temperature Processing and Mechanical Properties of Zirconia and Zirconia–Alumina Nanoceramics

The 1.5- to 3-mol%-Y₂O₃-stabilized tetragonal ZrO₂ (Y-TZP) and Al₂O₃/Y-TZP nanocomposite ceramics with 1 to 5 wt% of alumina were produced by a colloidal technique and low-temperature sintering. The influence of the ceramic processing conditions, resulting density, microstructure, and the alumina content on the hardness and toughness were determined. The densification of the zirconia (Y-TZP) ceramic at low temperatures was possible only when a highly uniform packing of the nanoaggregates was achieved in the green compacts. The bulk nanostructured 3-mol%-yttria-stabilized zirconia ceramic with an average grain size of 112 nm was shown to reach a hardness of 12.2 GPa and a fracture toughness of 9.3 MPa·m^1/2. The addition of alumina allowed the sintering process to be intensified. A nanograined bulk alumina/zirconia composite ceramic with an average grain size of 94 nm was obtained, and the hardness increased to 16.2 GPa. Nanograined tetragonal zirconia ceramics with a reduced yttria-stabilizer content were shown to reach fracture toughnesses between 12.6–14.8 MPa·m^1/2 (2Y-TZP) and 11.9–13.9 MPa·m^1/2 (1.5Y-TZP).     

电镀锡板表面抗划伤性的研究Ⅱ.软熔工艺对电镀锡板表面抗划伤性的影响

移植QHQ型涂膜铅笔划痕硬度仪用来测试电镀锡板的抗划伤性。用此方法研究了软熔处理以及不同软熔方式对电镀锡板抗划伤性的影响,实验结果表明：软熔处理对薄镀锡板可以提高镀锡板表面抗划伤性,在电阻软熔基础上增加感应软熔后,在一定条件下可进一步提高电镀锡板的抗划伤性,并从理论上进行了初步探讨。通过对电镀锡板表面形貌结果表明,表面抗划伤性与镀层晶粒大小和致密性有关。     

Fatigue behaviours of the zirconia dental restorations prepared by two manufacturing methods

The fatigue behaviours were evaluated on a novel zirconia dental restoration known as self-glazed zirconia (SG), prepared by a precision additive 3D gel deposition approach, compared with a conventional zirconia (CZ) restoration, shaped by CNC milling of zirconia blanks made by cold isostatic pressing. Eight fixed partial dentures made by each method were subjected to fracture test, without or with the application of 5-million fatigue cycles, respectively. The processing defects, grain size, and t–m phase transformation were examined by SEM and XRD. The results revealed that the fracture force of the SG restorations was higher than that of the CZ restorations in both cases, which ascribed to the fact that more voids and larger grains in the conventional versus in the SG restorations. The t–m phase transformation was observed only on the fracture surfaces of both materials subjected to fatigue test. Both zirconia restorations meet the clinical requirement.     

氧化锆用于牙修复的研究进展

由于氧化锆陶瓷具有高强度、高韧性和优良的生物相容性使其在生物材料应用领域占有重要地位。近几年来将其用于牙修复方面的报道日益增多。本文总结了氧化锆作为牙修复材料相对于其它修复材料的优点。概括了近年来国内外在氧化锆用于牙修复方面的研究现状,提出了还需要进一步研究的问题,并对其应用前景进行了展望。     

Analysis of the strain and hardness in self-cured and light-cured self-adhesive resin based cement

The study showed an application of the 3?D Digital Image Correlation Method (3?D-DIC) for detection of von Mises strain in samples of the self-etch, self-adhesive resin based cement (RBC). The aim was to determine and compare strain in the self-cured and light-cured Maxcem Elite, furthermore to investigate the hardness of these two cement-types. The experiment was carried out using two groups of Maxcem Elite (Kerr, Orange, CA, USA) samples; each tested group includes five (ø5?×?2?mm sized) samples, for both self-curing and light-curing mode. All samples were prepared by filling teflon ring-type molds. In addition, Vickers micro-hardness was measured for all samples. Maxcem Elite showed similar maximum strain values from 10% to 12% for both groups. Besides the maximum strain value, the 3?D-DIC method also enabled monitoring the change of strain field even after the recommended polymerization time. This method has shown that the polymerization shrinkage continues even after 10?min which disagreed with manufacturer’s suggestion. Group II showed maximum strain values of 12% in the peripheral zone after 10?min, in the last Stage (Stage 60). Statistically significant difference was not found in the overall strain between self- and light-cured Maxcem Elite neither peripherally (p?=?0.118) nor centrally (p?=?0.879). However, statistical significance was found in strain regarding central and peripheral zone in both, self-cured (p?=?0.020) and light-cured (p?=?0.002) Maxcem Elite. The mean von Mises strain values in the periphery of the samples (Section 0) were significantly higher compared to strain values in the center of the samples (for Section 1 and 2). The last stage (Stage 60) of the light-cured Maxcem Elite polymerization showed significantly higher values of von Mises strain compared to initial stage (Stage 0). Higher values of micro-hardness were noticed on the surfaces directly exposed to LED lamp after performing measurements of micro-hardness on light-cured samples.     

牙科用Y-TZP/云母微晶玻璃复合材料的研制

以K2O-MgO-Al2O3-SiO2-F系统的微晶玻璃为基础,与不同量的Y-TZP粉体进行复合,制备出了用于牙科修复的新型全瓷材料。借助于DTA,XRD,SEM等对该材料的主晶相种类和显微结构进行了研究,并测试了复合材料的抗折强度、体积密度、维氏硬度、热膨胀系数和耐酸(碱)性等理化性能。实验结果表明:复合材料的主晶相为氟金云母、t-ZrO2和少量的m-ZrO2;其具有优于天然牙齿和牙釉质的力学性能,化学性能稳定、审美效果良好,适用于制作前牙冠、贴面、嵌体等口腔修复体。     

如何提高单组分水性木器漆硬度及耐划伤性

讨论了影响水性木器漆硬度及耐划伤性的因素、硬度与耐划伤性的关系、水性树脂的选择及助剂的搭配以及对最终产品性能的影响。指出了水性木器漆的硬度、耐划伤性的重要性。     

Methods for studying the mechanical and tribological properties of hard and soft coatings with a nano-indenter

This study illustrates the capabilities of a nanoindentation/nanoscratch tester to assess mechanical and tribological properties of coating films. Properties such as hardness, elastic modulus, mar and scratch resistance, and critical force for cracking can be accurately measured. Operation of the Nano-Indenter is described in detail. A scanning probe microscope (SPM) is shown to be a valuable supplement to the Nano-Indenter. Well-characterized thermoset acrylic clearcoats and thermoplastic latex films were studied. For the first time, operating parameters are described for measurement of relatively soft coatings, such as films cast from a latex with a glass transition temperature (T_g) of 8°C. Thus, the method is made available for study of most types of coatings. The method can easily discriminate between coatings with different T_gs and crosslink densities. Once operating parameters are established, it takes about 10 minutes for an indentation test and 10 minutes for a scratch test with the Nano-Indenter, and with further automation this time could be reduced. Each indentation test accurately measures hardness and elastic modulus as a function of depth within the coating, and each scratch test provides additional insight into the material’s behavior. The method is sensitive to small changes in polymer composition and formulation, and results are highly reproducible. Presented at the 81st Annual Meeting of the Federation of Societies for Coatings Technology, November 12–14, 2003, in Philadelphia, PA.     

Temperature Dependence of Hardness in Yttria-Stabilized Zirconia Single Crystals

The temperature dependence of hardness and microcracking in single-crystal 9.5-mol%-Y₂O₃-fully-stabilized cubic-ZrO₂ was studied as a function of orientation. Crack lengths increased with increased temperature up to 500°C; above 800°C, no cracks were found, indicating an indentation brittle-to-ductile transition of ∼800°C. The temperature dependence of hardness was reduced around 500°C. Etching studies to delineate the plastic zone around and below indents identified the operative slip systems. The role of dislocations and their interactions within the plastic zone on the hardness and indentation fracture behavior of cubic-ZrO₂ are discussed.     

牙科用TZP陶瓷的基本性能的研究

本研究采用化学共沉淀法制备氧化锆粉体 ,135 0℃烧结。测得弯曲强度为 70 9MPa ,断裂韧性为 11.6MPam1/2 。Ce -Y -Mg复合稳定剂可以对ZrO2 起到很好的稳定作用 ;弯曲强度和断裂韧性均为桩钉材料重要指标 ,桩钉材料的断裂韧性越高越好 ,而强度要适当。Ce -Y -Mg复合稳定TZP韧性好 ,较其它TZP高 ,有可能成为牙科桩钉材料。     

Hyperbranched Polyether as a Modifying Agent for Urea-Formaldehyde Resins—Hardness and Strength Control Tool

A commercially available urea-formaldehyde (UF) resin was blended with a hyperbranched polyether (HBP) obtained from glycerol being a by-product in biodiesel production. The mechanical properties of the cured polymeric blends are described in this article. It was found that low addition (3 wt%) of the modifier significantly improves the hardness (16%) and the compressive shear strength (17%) of the polymer, whereas water absorption remains unaffected. It was also shown that blending UF resins with hyperbranched polyethers can be an effective tool for controlling mechanical properties and dimensional stability of the polymeric systems.     

Surface plasticisation of nylon 6,6 by water

Tribological studies have been carried out on Nylon 6,6 with particular emphasis placed on the examination of the effect of water on this polymer. An examination of the sliding frictional behaviour of Nylon 6,6 against a steel substrate shows that the friction decreases with increasing load, probably due to the formation of thermally softened interfaces in the contact. After exposure of this polymer to water, dramatic changes to the frictional behaviour of the Nylon are observed; the friction increases with increasing load. From the application of the adhesion model of friction it is postulated that the observed changes are caused by extensive plasticisation of the Nylon and, as a consequence, an increase in the contact area. This proposition is confirmed by the reported scratch hardness data. After treatment with water the scratch friction mechanism changes significantly and a notable reduction in the hardness of Nylon is observed.     

Temperature-Dependent Indentation Behavior of Transformation-Toughened Zirconia-Based Ceramics

Indentation behavior of Ce-TZP, Y-TZP, and Mg-PSZ between room temperature and 1300°C was investigated. Hardness decreased with increasing temperature for all three materials, but indentation cracking increased with increasing temperature. The opposing temperature dependences are discussed in terms of dislocation and transformation plasticity.