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1.
本文介绍了现有的传统陶瓷产品耐磨性能测试方法与标准,分析了这些测试方法用于测试传统陶瓷耐磨性能的可行性和不足之处,提出可以统一有釉砖与无釉砖耐磨性能测试方法与标准。 相似文献
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超声导波检测技术是一种新型的长距离、快速检测手段。对影响超声导波检测结果的诸多因素进行了分析。在管线运行的状态下,利用MsS导波技术可以进行长距离管壁腐蚀等缺陷的检测。但该技术无法定量给出缺陷的形状、大小和性质,且具有诸多局限性,因而该技术的应用宜结合其他无损检测方法进行复验确认。 相似文献
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Al2O3基泡沫陶瓷的研究 总被引:5,自引:0,他引:5
以Al2O3和锆英石为主要原料制备了具较高强度及抗热震性的泡沫陶瓷并进行了性能研究与应用试验。结果表明:当锆英石含量为30%时,材料的抗弯强度最大,达3.84MPa;随锆英石含量的提高,抗热震性能增强;泡沫陶瓷的孔隙率与锆英石含量无关,为80-81%,泡沫陶瓷过滤器能有效滤除铸液中夹杂物。 相似文献
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陶瓷涂层以其优异的耐磨损、耐高温、耐腐蚀等性能表现出巨大的工程应用前景。但是,在服役过程中因温度变化和受力诱发的裂纹产生、扩展,甚至导致涂层开裂、剥落及失效,这些因素限制了涂层的应用,因此通过结构优化改善陶瓷涂层的抗开裂、剥落性能较为重要。本文首先论述了纳米结构涂层、耐磨多层涂层、复合涂层的失效机理及其结构优化。提出了利用单次喷涂制备粘结层和陶瓷层的方法,通过该方法可以消除陶瓷层与粘结层间的界面形态,提高涂层的断裂韧性、粘结强度。最后展望了陶瓷涂层在材料组分设计和工艺优化研究中应重点关注的方面。 相似文献
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文章综合论述了纳米陶瓷结合剂的性能特点、增强增韧机理以及研究进展,并探讨了纳米陶瓷结合剂cBN砂轮制备过程中存在的问题及对策,指出纳米陶瓷结合剂不仅可以解决目前陶瓷结合剂低熔点与高强度之间的矛盾,而且对于拓宽cBN砂轮的应用范围、适应超高速磨削技术具有十分重要的意义。 相似文献
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《Journal of Adhesion Science and Technology》2013,27(7):647-660
Aerospace structures use polymeric composite materials extensively. These composite materials are normally bonded together by adhesives to form structural parts. The existence of any kind of defects or discontinuities in the bonds is completely undesirable for such applications. Ultrasonic imaging (UI) is a widely used technique for non-destructive evaluation (NDE) and can be adopted to evaluate the integrity of such adhesively-bonded joints. However, characterization of adhesive bonds in composite materials using UI has deficiencies due to problems such as high acoustic attenuation and high signal-to-noise ratio. These problems can be attributed to the inhomogeneity in composite structures. The present study addresses the problems of detection of disbonds and porosity in adhesively bonded carbon fiber reinforced composite panels. Five sets of adhesively-joined carbon/epoxy composites with different adherend surface preparations were fabricated and subjected to UI. The panels contained known defects in the bondline of the samples. UI results are interpreted to identify various existing defects such as voids, cracks and disbonds in the joints. Attenuation coefficient values for all types of composites are utilized to ascertain the validity of the image analysis. 相似文献
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The objective of any system of non-destructively examining an adhesive joint must be to obtain a direct correlation between the strength of the joint and some mechanical, physical or chemical parameter which can readily be measured without causing damage. Faults or defects are defined as anything which adversely affect the short or long term strength of a joint. There are two basic areas for examination, the cohesive strength of the polymeric adhesive, and the adhesive strength of the bond between polymer and substrate.
Adhesive strength is very difficult to measure since it is an interfacial phenomenon involving a very thin layer of material, thin even in comparison with bond-line dimensions. Effectively, it would be necessary to assess intermolecular forces and this is not readily possible with existing techniques. This aspect of quality control is usually reduced to assessing the nature of the adherend surfaces prior to bonding.
The cohesive strength of the adhesive is really the only parameter which can be estimated with any degree of confidence, and it is this which features most on destructive tests of bonded joints.
In this paper, defects including porosity, surface un-bonds, zero-volume unbonds, poor cure and so on are discussed, together with the various methods currently used (and some new methods) for physical non-destructive testing. 相似文献
Adhesive strength is very difficult to measure since it is an interfacial phenomenon involving a very thin layer of material, thin even in comparison with bond-line dimensions. Effectively, it would be necessary to assess intermolecular forces and this is not readily possible with existing techniques. This aspect of quality control is usually reduced to assessing the nature of the adherend surfaces prior to bonding.
The cohesive strength of the adhesive is really the only parameter which can be estimated with any degree of confidence, and it is this which features most on destructive tests of bonded joints.
In this paper, defects including porosity, surface un-bonds, zero-volume unbonds, poor cure and so on are discussed, together with the various methods currently used (and some new methods) for physical non-destructive testing. 相似文献
11.
Emanuela Craciunescu Cosmin Sinescu Meda Lavinia Negrutiu Daniela Maria Pop Hans-Christoph Lauer Mihai Rominu 《Journal of Adhesion Science and Technology》2016,30(6):666-676
All ceramic systems are replacing the classical metal–ceramic crowns in dental practice. Zirconium dioxide (zirconia) core associated with veneering ceramic provides both good mechanical and aesthetic properties of prosthetic restorations. However, such zirconia crowns may be affected by defects of adaptation, too tight contacts in the proximal area and fissures of the ceramic veneer. The latter produces chipping; this requires a reattachment, therefore a second burning of the zirconia–ceramic interface. Such an additional procedure may affect the mechanical resistance of the ceramic veneer and the bond between the zirconia core and the ceramic veneer. The aim of this study was to evaluate the alterations of this shear bond strength (SB) between the zirconia core and the ceramic veneer, as produced by the first set of complete burning procedures and by the second correction burning of the dental restorations. Thirty-three zirconia discs were veneered with ceramic material and the SB was evaluated for each sample. Each ceramic cylinder detached from the zirconia was bonded on the core through a new layer of dentin and another burning procedure; the SB was tested again. The results of the two SB tests were compared; the statistical analysis concluded that there is an approximately 10% decrease of the resistance after the second burning. Also, the spread of the values for each test showed the high impact of the human factor on such dental restorations. In all the tests, the weakest area proved to be the interface between the zirconia core and the layered ceramics. 相似文献
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The objective of any system of non-destructively examining an adhesive joint must be to obtain a direct correlation between the strength of the joint and some mechanical, physical or chemical parameter which can readily be measured without causing damage. Faults or defects are defined as anything which adversely affect the short or long term strength of a joint. There are two basic areas for examination, the cohesive strength of the polymeric adhesive, and the adhesive strength of the bond between polymer and substrate. Adhesive strength is very difficult to measure since it is an interfacial phenomenon involving a very thin layer of material, thin even in comparison with bond-line dimensions. Effectively, it would be necessary to assess intermolecular forces and this is not readily possible with existing techniques. This aspect of quality control is usually reduced to assessing the nature of the adherend surfaces prior to bonding. The cohesive strength of the adhesive is really the only parameter which can be estimated with any degree of confidence, and it is this which features most on destructive tests of bonded joints. In this paper, defects including porosity, surface un-bonds, zero-volume unbonds, poor cure and so on are discussed, together with the various methods currently used (and some new methods) for physical non-destructive testing. 相似文献
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The processes affecting the cold resistance of ceramic wall products are examined from the standpoint of irreversibility,
nonequilibrium, and synergetics. The conditions necessary to assure high cold resistance are found to be a pore structure
and pore surface properties such that, in service, ice would form low-strength structures and the resultant stresses would
relax at the expense of the ice rather than the ceramic material.
Translated from Steklo i Keramika, No. 3, pp. 12–15, March, 1997. 相似文献
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陶瓷纤维是一种集传统绝热材料、耐火材料优良性能于一体的纤维状轻质耐火材料,陶瓷纤维具有重量轻、耐高温、热稳定性好、导热率低、比热小及耐机械震动等优点,因而其产品涉及各领域,发展前景十分看好。本文分别介绍了陶瓷纤维的种类及性能特点,陶瓷纤维的结构性质和制造方法;陶瓷纤维的主要用途和应用范围;以及陶瓷纤维在热工窑炉中的应用技术;同时指出了陶瓷纤维的发展趋势。 相似文献
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介绍了国产连续碳化硅(SiC)纤维的研究进展及国外连续碳化硅纤维产品的主要应用,展望了国内连续SiC纤维及其产品的发展趋势.表明SiC纤维具有高比强度、高比模量、耐高温、抗氧化、抗蠕变、耐化学腐蚀、耐盐雾和优良的电磁吸收特性,是耐高温陶瓷基复合材料的关键材料. 相似文献
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《Journal of the European Ceramic Society》2022,42(2):525-533
Dielectric constants of Al2O3 (alumina) ceramic samples have been measured with non-destructive terahertz time-domain spectroscopy. Using an effective medium approximation, we demonstrated that the relative permittivity can be used to evaluate the porous alumina samples, with porosity fractions ranging from 0% to 20% per volume. This result makes it possible to control sample porosity, a key material parameter related to mechanical strength under compression load, hardness and wear resistance, or thermal stability. We also employed terahertz time-domain spectroscopy to differentiate alumina samples fabricated with different grain sizes, or reveal a small fraction of impurities, such as 5%vol of ZrO2, embedded in non-porous alumina. These results demonstrated the potential of terahertz radiation for non-destructive characterization of low loss high dielectric constant ceramics. 相似文献
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《Journal of the European Ceramic Society》2020,40(3):636-641
Determining the effect of defects in fiber-reinforced materials, such as polymer matrix composites (PMCs), can be studied by creating artificial flaws in these materials, for example by introducing artificial PTFE foil to induce material delaminations. For fiber-reinforced ceramics (CMCs), this approach is more difficult due to the more complicated production routes of CMCs, which involve several processing steps at elevated temperatures. This work deals with the fabrication and introduction of defined defects in carbon fiber reinforced silicon carbide (C/C-SiC) composites in a way, which allows their detection by non-destructive material testing methods during and after each production step of the composite. It was shown that the defects produced using boron nitride (BN) and alumina fiber roving were stable over the entire manufacturing process and could be detected by ultrasound and x-ray tomography techniques. To determine any possible effects, an initial sampling of bending samples with artificial defects was manufactured, tested and compared with defect-free reference materials. These tests showed a lower bending strength and failure strain for the defect samples compared to samples without defects. 相似文献
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Yasushi Ikeda Yasutoshi Mizuta Katsuhiro Onda 《Journal of the American Ceramic Society》1999,82(4):882-888
A new microfocus X-ray testing method has been developed to detect very small defects in ceramic products with high speed and reliability. By using image subtraction, enhanced X-ray images of defects were extracted from the background noise. Much-better sensitivity (e.g., 0.1% in Si3 N4 that was 20 mm thick) was obtained within a few minutes. This method is considerably superior to the conventional film method. In this study, Si3 N4 test pieces (penetrameters) that had very small artificial defects (such as slits and pores) were prepared and examined by using the new method. 相似文献