轮胎模具DLC涂层应用的可行性分析

为了探究类金刚石(DLC)涂层在轮胎模具上应用的可行性,以35钢为基体,采用等离子辅助增强化学气相沉积(PECVD)的方法分别制备出了含氢类金刚石(DLC)涂层和氟化类金刚石(F-DLC)涂层,并对涂层表面形貌、Raman光谱、表面粗糙度、结合强度、力学性能、摩擦磨损性能进行了研究分析。结果表明:所制备的含氢DLC涂层和F-DLC涂层表面粗糙度分别为53.2 nm和54.6 nm,表面光滑,致密性好;涂层接触角分别为81.2°和98.5°,符合脱模要求;纳米硬度分别为23.9 GPa和14.3 GPa,弹性模量分别为177.0 GPa和118.5 GPa,拥有较高的结合强度和力学性能;在140℃下进行摩擦磨损试验时的摩擦系数分别为0.448 7和0.263 1,磨损不明显,具有良好的抗磨减摩特性。采用该工艺方法来制备轮胎模具DLC涂层具有应用的可行性。     

无氢DLC涂层的摩擦学性能

为了探究轮胎模具无氢类金刚石(DLC)涂层的摩擦学特性,增强轮胎模具的易脱模、防粘、自清洁性能以及提高轮胎质量与服役寿命,以轮胎模具常用的35钢为基体,利用电弧离子镀在基体试样上制备无氢DLC涂层,对涂层Raman光谱、表面粗糙度、表面微观形貌、纳米硬度、结合力和摩擦系数进行了分析,着重研究涂层摩擦前后表面微观形貌的变化以及摩擦磨损机理。结果表明:通过改变表面粗糙度可以有效降低涂层的摩擦系数,涂层摩擦系数随粗糙度减小而显著降低;在140℃高温条件下,摩擦系数最小低至0.363 4,且涂层纳米硬度可达32.45 GPa,弹性模量高达348.94 GPa。无氢DLC涂层完全满足轮胎模具减摩耐磨和自清洁性的使用要求,为制造高性能轮胎模具提供了一种可行的工艺选择。     

轮胎模具无氢DLC涂层的制备及表征

为探究轮胎模具类金刚石(DLC)涂层的应用前景,提高模具表面的硬度和疏水性,按照模具加工工艺制备35钢基体试样,利用电弧离子镀在基体上沉积无氢DLC涂层,对涂层粗糙度、三维表面形貌、断面结构、元素组成及含量、Raman光谱、纳米硬度和疏水性进行了分析.结果表明:通过改变粗糙度可以改善涂层的疏水性,涂层疏水性随粗糙度增大而显著增加,水接触角最高可达96°,且涂层硬度可达30.3 GPa.无氢DLC涂层可满足轮胎模具耐磨性和易清洁的使用要求,为制造高性能轮胎模具提供了一种可行的工艺选择.     

轮胎模具DLC涂层的制备及性能

为探究高性能轮胎模具类金刚石(DLC)涂层的应用前景,提高模具花纹块内表面的疏水性及耐磨减摩性,采用等离子体增强化学气相沉积法在35钢基体上制备DLC涂层,并对所制备的DLC涂层的表面形貌、粗糙度、疏水性、表面元素组成、纳米硬度、摩擦系数等关键指标进行了测定.结果表明:DLC涂层具有优良的表面完整性,水接触角可达19.62°,乙醇接触角达20.37°,纳米硬度可达19.62 GPa,摩擦系数低至0.405 8,DLC涂层有望替代Teflon涂层,用于高性能轮胎模具.     

DLC、Teflon涂层形貌及性能参数对比研究

为探究类金刚石(DLC)涂层替代Teflon涂层应用于轮胎模具的可能性,解决Teflon涂层耐磨性差、寿命短、清洗复杂的问题,对DLC与Teflon涂层的形貌(表面形貌、断面结构)及性能参数(疏水性、结合力、硬度、坯胎-涂层摩擦系数)进行对比试验。结果表明,在疏水性与摩擦系数方面,DLC涂层与Teflon涂层基本相当;在表面硬度与其他方面,DLC涂层优于Teflon涂层。从对比试验结果而言,DLC涂层替代Teflon涂层应用于轮胎模具具有可行性。     

环氧底漆表面合成超疏水涂层减阻性能研究

采用大气压冷弧等离子体射流在防腐涂料表面制备了超疏水涂层。利用接触角仪对涂层的疏水性能进行了检测,并利用扫描电镜、能量色散谱对涂层表面形貌和化学成分进行了表征,采用差压流阻测试仪研究了等离子处理前后试样表面的减阻效果。结果表明,经等离子体射流处理后的涂层表面水接触角大于160°,滚动角小于5°,且该超疏水涂层在大气中具有良好的稳定性。流阻测试实验证明等离子射流处理后的试样表面减阻率最大可达16.5%。涂层具有微米和纳米凸起的二元复合结构,大幅度降低了涂层的表面能,二元结构中形成的空气层,将固体与液体之间的摩擦转化为气体与液体之间的摩擦,有效降低了水在超疏水涂层表面的运动阻力。     

复合氟化改性制备EP-ZnO纳米超疏水涂层的研究

风力发电机叶片覆冰严重影响风机安全经济运行,高质量的超疏水防冰涂层是当前研究的热点之一.本实验采用复合氟化改性的方法分别对环氧树脂(EP)和固化剂进行氟化改性,同时通过ZnO纳米颗粒对涂层表面结构进行修饰制备EP?ZnO纳米复合超疏水涂层,并研究了涂层的疏水性、耐磨性和抗冲击性能.研究结果表明,复合氟化改性能有效提高涂层的疏水性能,其接触角为150°,滚动角为6°;经过ZnO纳米颗粒对涂层表面结构修饰后涂层的接触角达158°,滚动角为3°.涂层具有良好的粘附力、稳定的抗冲击能力和耐磨性能,在磨损实验过后,涂层仍能保持较高的疏水性能.     

微纳米颗粒/硬脂酸超疏水涂层的仿生构建及其性能研究

通过一步喷涂法将微纳米表面构建与低表面能物质修饰相结合,制备了超疏水仿生涂层;开展超疏水材料涂覆技术研究,分析总结不同涂敷方式对涂层的性能影响;测定了不同粉体种类与浓度下涂层的疏水性能差异,分析评价其对涂层疏水性能的影响;优选涂层材料配比对混凝土试块进行疏水改性,并测试其防污性能;通过LW-AB法表面能计算,探讨了涂层粗糙度与表面能之间的关系,并使用SEM对其表面微观形貌进行了表征。结果表明,在添加微纳米颗粒的情况下,喷涂制备的涂层接触角比浸涂制备的涂层大1/3左右,滚动角比浸涂制备的涂层小85%以上,体现了较好的疏水性能;涂层的疏水性能受表面能与粗糙度的影响,且随着硬脂酸浓度的增加、粉体浓度的增加与粉体颗粒粒径的减小,涂层的疏水性能呈增强的趋势,接触角达到165.27°,滚动角低至0.9°;经过超疏水处理后,混凝土试块表现出明显的防污与自清洁性能;表面能计算表明,在添加同样硬脂酸含量的条件下,随着粗糙度的增加,涂层表面的降低至4.89 mJ/m~2,仅为纯硬脂酸涂层的26.84%。     

PVDF/SiO2/PDMS涂层超疏水纺织品性能

目的 针对普通纺织品材料防水性和防污性较差的问题,制备具有自清洁功能的超疏水涂层纺织品,并研究其性能.方法 以涤纶织物为基材,通过非溶剂诱导相分离法,使用聚偏氟乙烯和疏水纳米二氧化硅复合液在纺织品表面构筑微纳粗糙结构,采用聚二甲基硅氧烷对其进行疏水化处理,获得自清洁超疏水涂层纺织品.采用扫描电子显微镜、X射线能量散射光谱和视频光学接触角测量仪等对其结构和性能进行表征,并通过机械摩擦、洗涤、酸/碱/盐溶液浸渍和紫外光照等方法对其表面超疏水稳定性进行考察.结果 当聚偏氟乙烯质量分数为2％,疏水纳米二氧化硅质量分数为0.4％,聚二甲基硅氧烷质量分数为1％时,制备的纺织品的表面接触角可达(162.2°±0.8°),滚动角达(2.0°±0.4°),具有优异的超疏水自清洁效应;经72 h酸/碱/盐溶液浸渍、196 h紫外光照、2500次摩擦和120次家庭水洗后,其表面接触角仍大于150°,表现出优异的超疏水稳定性.结论 采用简便的非溶剂相分离法制备的涂层纺织品具有优异的自清洁性能,并且其超疏水性能具有机械耐久性和化学稳定性,有望应用于纺织材料包装领域.     

仿生超疏水涂层的制备及其性能

目前,超疏水涂层多采用含氟低表面能化合物制备,成本较高,工艺较复杂,限制了其推广应用.为此,通过在环氧酚醛涂料中加入具有疏水作用的表面活性剂和微米轻质碳酸钙颗粒改变涂料的表面状态,在碳钢表面制备了具有仿荷叶表面结构的疏水涂层.利用扫描电镜和接触角测定仪对涂层的表面形貌和疏水性能进行了表征.结果表明:涂层的结构与荷叶表面的的乳突结构具有较好的一致性,水滴在涂层表面的接触角得到了显著提高;涂层具有良好的疏水功能.     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Analysis of anisotropy of properties on the basis of studies of texture of coarse-grained ingots of thermoelectric materials

An analysis of anisotropy of the properties of a Bi₂Se_0.3Te_2.7 solid solution was carried out using construction of demonstrative surfaces for thermoelectric effectiveness and thermal expansion coefficients. It is shown that the texture is an important factor forming anisotropy of properties and technological fitness of ingots for manufacturing modules. Anisotropy of properties based on the studies of the ingot textures obtained using the float-zone method and Bridgman method (growing thermoelectric plates in a flat cavity) was studied.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.