Advanced Materials Research Vols. 476-478

Abstract: Multilayers of CrN/Si3N4 coatings were prepared by magnetron sputtering on die steel substrates. The layers of CrN/Si3N4 films were varied to investigate their effects on microstructure, morphology, nano-hardness properties determined by X-ray diffraction, field-emission scanning electron microscope (FE-SEM), nanoindentation, and pin-on-disk, respectively. The result shows that CrN has highly (111) preferred orientation and Si3N4 exhibits amorphous phase at working temperature of 200 oC. The surface of coatings revealed smaller grains and uniform dense with higher layers. The number of layers increased with enhancing of the mechanical properties, and hardness values. At 64 layers films had the largest nano-hardness. Besides, the highest layers of CrN/Si3N4 multilayers have been achieved the lowest friction coefficient for against steel ball.

Abstract: A new test method of metal magnetic memory (MMM) was designed and was applied to study the relationship between MMM signals distortion and uneven plastic deformation so as to obtain the direct evidence of the result that MMM signals change unevenly causing by the unevenly plastic deformation in tensile test. Macro magnetic memory measurement were done to capture the occurrence time and position of MMM signals’ distortion during the period of plastic deformation, strain measurement were done before each MMM measurement and micro slip lines were observed after each time when MMM signals were measured to capture the occurrence time and position of plastic deformation. Then direct evidence can be obtained by compared the consistency of the time and positions. Preliminary tests were done to prove the rationality and feasibility of the new test method. The results show that the evidence can be obtained effectively and change law of MMM signals were reproduced by this new test method.

Abstract: CO2 corrosion for rubber materials makes sealing failure of downwell tools and annulus pressure even, which will endanger the safety production of gas injection wells. The high-temperature high-pressure autoclave was used to test supercritical CO2 corrosion for dumbbell-shaped hydronibrile nitrile with pressure 35MPa, temperature 90°C. The change in mechanical properties and corrosion morphology had been analyzed and compared before and after corrosion test in gas and liquid phase environment. Experimental results show that the hardness of hydronibrile nitrile was hardly changed and no dissolution occurred after corrosion. But the tensile strength decreased by 50%. In engineering design, the influence of corrosion on mechanical properties of rubber should be fully considered, and the mechanical properties of rubber in origin state should not be taken as the basis. The research results have provided evidence for the use of rubber materials in CO2 corrosion environment.

Abstract: The scale application of wind energy conforms to the demand of sustainable development in our country. However, with the blower’s blade lengthened, the weight will also increase. If it is made in traditional way, it would reach tons of orders of magnitude, and the centrifugal force on the blade root will become very large because of the tip speed ratio. When the wind is large enough, the blade force model is equivalent to a cantilever beam structure, thus the material of extended wind turbine blade should possess high strength and high modulus and should be light. Otherwise the blade’s life will be shortened [1]. In many of the materials, the multi-axial fabric is a good carrier to meet these requirements. If the blade in the extended length also can meet the strength requirements, the multi-axial fabric will be the top choice for future wind-driven generator blade design and manufacture.

Abstract: Ultrasonic guided wave method used for detection of cracks in the desuperheater header and main steam pipes of boiler in power plants has been reported. The dispersion curves of the guided wave for the main steam pipe were calculated and the wave modes used for the detection of notches were verified experimentally. One defect was found at the welded joint of the low temperature pipe on the furnace side. The time of flight diffraction (TOFD) was also carried out to verify the experimental results. The length, depth and height of the defect are 1200 mm, 18.9 mm and 5.5 mm, respectively. And one circular crack was found inside of the desuperheater header.

Abstract: Chemical cure shrinkage of polymer matrix is a significant source of residual strain formation in composite products during curing. In this paper, fiber Bragg grating (FBG) sensors were used to monitor the free strain development caused by chemical shrinkage and compared with results of differential scanning calorimetry and rheological analysis. The results showed that the gel point could be clearly identified by FBG sensors and compressive residual strain of around 800με was caused by isothermal curing reaction after gelation. The relationship between the chemical shrinkage ratio and conversion degree was found to be nonlinear.

Abstract: Roll rings are important parts in bars, and wire rolling, and their number consumed is large. They can fail and fracture due to defects of their own material and poor working conditions. There are many measures to prolong service life of roll rings, for example, their correct use and maintenance, suitable material, advanced manufacturing technology, and well machining quality, but mixed wear is inevitable. Such problems as surface defects and negative deviation of roll’s diameter caused by mixed wear can be solved by advanced repairing technology to make them meet users’ requirements, and prolong service life.

Abstract: Characterization of the surface morphology after CMP vital refers to the roughness of surface outline at present. The two dimensional parameters characterization based on scanning the outline of surface as the test foundation already cannot satisfy the requirements of engineering; hence three dimensional detection and quantitative calculation of surface morphology can complete characterization. Characterization of surface morphology has made great development from low to high precision accuracy, from a single variety of touch probe to optical, atomic force, and other varieties, from the contact to non-contact, from two dimensions to three dimensions, from a single roughness measurement to simultaneously measurement of waviness, shape error outline information. Scanning probe microscopy can give surface topography of the whole measured area. Because discrimination all can reach the nanometer level surface roughness in x, y and z three directions, Scanning probe microscopy is suitable for measured structure with vertical structure units in nm magnitude and horizontal area in μm scale.

Abstract: In order to measure 3D residual stress accurately with layer stripping method, this paper proposes a series of elastic mechanics hypothesis and deduces a set of correction formulas based on the model of cylinder with limitless length. The formulas are expressed as discrete form. When the thickness of removed layer is infinitesimal, the discrete formulas agree with the existing integral formula. This paper also gives an engineering example and verifies the importance of residual stress correction.

Abstract: This paper will introduce the application status of the wind door of the underground coal mine, the structure and composition, the working principle, the hydraulic system, and the electrical control system of the automatic wind door which is controlled by PLC. This paper will focus on the design of the programmable controller program and show the ladder diagram of the corresponding program and the outer way of wiring.