Advanced Materials Research Vol. 413

Abstract: SiC_p/Mg-Al composites with 5μm 2wt.% SiC particles as reinforcement were prepared under the protection of inorganic flux. The microstructures, textures and components of the composites were investigated using optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD) and backscattered electron imaging (BSE). The results indicate that SiC particles are mainly distributed along grain boundaries, retarding grain growth and conducing to the refinement of the matrix. Interfacial reaction can occur between SiC_p and Mg but not between SiC_p and Al. There are α-Mg and β-Mg₁₇Al₁₂ phases, γ-MgAl phase, α-Al and β-Al₃Mg₂ phases in SiC_p/Mg-Al composites with the Mg/Al ratio of 4/1, 1/1, 1/4 respectively.

Abstract: In this paper, experimental study of the microwave reflection behavior in MRF was carried out. The results showed that at the same frequency the microwave reflectivity of MRF decreased with the increasing of magnetic field strength; and with the increasing of particle concentration, microwave reflectivity decreased, monotonously. Under the given magnetic field, with the increasing of microwave frequency, it first decreased, there is a lowest point at 9.2GHz, and then it increased. Usually, it is considered that the change of internal structure of MRF under external magnetic field is the main reason for the regulation behavior of microwave reflectivity.

Abstract: Adsorption of three different source humic acid (HAⅠ:shaihai JuFeng Technology Co., Ltd,china; HAⅡ:Sigma,American; HAⅢ:Lingshi hope preparation plant,Japan) in wastewater by Cucurbiturils was explored. The factors of effect of the removal rate of HA, such as amount of initial adsorbent,HA concentration, and pH values were investigated. The results of adsorption show that:the maximum capacity of HAⅠ,HAⅡ,HAⅢ at equilibrium (Q_e) and percentage of adsor-ption (η/%) are 9.88 mg·g^-1(99.59%), 8.22 mg·g^-1(99.84%),8.19 mg·g^-1 (99.39%), respectively, when HA concentration, temperature, pH value and fixed adsorbent dose are 10 mg·L^-1, 298 K, 6.5 and 2.4g·L^-1; Adsorption amount of HA over cucurbiturils decreased with the increasing of solution pH,and increased with increasing of cation concentration;Adsorption amount of HA on cucurbiturils after four successive adsorption regeneration cycles was decreased from16.29mg·g^-1 to 11.45mg·g^-1. In conclusion,we found that the Cucurbiturils were significantly effective for the removal of HA and can be recycled from wastewater.

Abstract: Failure in anisotropic/isotropic bi-materials starts at the interface, and the interfacial failure is of interest to some engineering fields such as automobile and aviation industry. Many researchers have done a lot of research on this field, but many did not consider a specific stress component near the interface corner tip as a parameter of a failure criterion. Kun Cheol Shin, introducted a failure criterion for anisotropic/isotropic bi-materials problem with a wedge. But the process of obtaining the singular stress fields of anisotropic/isotropic bi-materials is complex. To solve this problem, we have taken a new method which is from Xuecheng-Ping and M.-C. Chen.The method is new, which is based on displacement and more easily in calculating the stress and displacement fields surrounding a wedge tip than before. Through this method, we establish a criterion base on the-plan. The failure criterion can be used not only to predict stress intensities of co-cured double lap joints that with thermal and mechanical load, but also to predict stress intensities of co-cured double lap joints that with different materials or lap length. And we describe the process of calculating singular stress fields and stress intensities of co-cured double lap joints with a wedge that consists of glass fiber reinforced composites and steel adherends.

Abstract: In the last decade, or so, many prototype Silicon Carbide devices and circuits have been demonstrated which have surpassed the performance of Silicon for the ability to function in extreme environments. However, the commercialisation of SiC technology now demands high performance and energy efficient miniaturised devices and circuits which can operate on the limited power resources available in harsh and hot hostile environments. This leads to refining, experimenting and perhaps re-designing devices which can rightly claim their share in the current Si dominant market. Consequently, there is a need for accurate simulation models for device engineers to understand device behaviour, examine performance trade-offs and verify the manufacturability of the design. This paper reports the first comprehensive study on the development and validation of high temperature 4H-SiC Technology Computer Aided Design (TCAD) Finite Element simulation model for low power applications. The model is based on 4H-SiC physical and material properties and is validated by high temperature 4H-SiC lateral JFET data, fabricated and characterised by our group at Newcastle University.

Abstract: The application conditions of acoustic emission technique in mines are the base of acoustic emission monitoring coal and rock and gas dynamic disasters, which must be studied before acoustic emission monitoring gas dynamic disasters in the field begins. Based on the stress wave propagation theory, quality factor Q theory, and many field tests, the acoustic emission propagation theoretic model is established, and the acoustic emission propagation laws in coal and rock with the different protodyakonov coefficient are obtained. Based on these propagation laws and monitoring techniques in the field, the application conditions of acoustic emission monitoring dynamic disasters in the coal and rock are preliminarily given, which can be described that, when the protodyakonov coefficient of coal is smaller than 0.2, acoustic emission sensors must be installed in roof rock; when the protodyakonov coefficient of hardness of coal is not less than 0.2, acoustic emission sensors can be installed in the roof rock or in the coal. These conclusions support the theoretic and testing base for the further study on the acoustic emission forecasting dynamic disasters technique.

Abstract: Liquid wear-resistant technology combines original decorative paper and the surface wear-resistant paper into one. Wear-resistant particles are coated directly on the surface of base decorative paper, forming a transparent wear-resistant protective layer. The suspension behavior of ultra-fine A1₂O₃ in the aqueous phase was investigated. The aim was further realizing the good consistency among A1₂O₃, melamine resin and other components. The main influencing factors [viz., dispersant type, dispersant dosage, dispersive methods and pH value] were investigated to get the optimum conditions. The results showed that the stable aqueous suspension of ultrafine A1₂O₃ could be obtained under the following conditions: the concentration of superfine A1₂O₃ 5wt%, pH = 9, anionic dispersant APAAA, the amount of dispersant 0.4wt%, ultrasonic suspension time 30min.

Abstract: According to the low temperature disease on asphalt pavement in the areas of cold and large temperature difference between day and night, conventional index test and low temperature bending creep test were used to analyze the influence of diatomite dosage on the low temperature performance of diatomite modified asphalt, and the mixture’s low temperature bending test was applied for verification. Test results show that after diatomite’s addition into asphalt, equivalent brittle point reduces significantly, ductility test cannot estimate low temperature performance very well, stiffness modulus increases and relaxation ability decreases; meanwhile, peak value of stiffness modulus and strain energy of asphalt mixture can be found, the low temperature crack resistance is enhanced; optimum dosage of diatomite is 13%. So, the low temperature performance evaluation method of diatomite modified asphalt mixture through BBR’s low temperature performance evaluation on diatomite modified asphalt remains to be discussed.

Abstract: A test section was selected in Luo-San expressway.Four detection methods of compaction degree which are sand cone method, cutting ring, nuclear density instrument and drop hammer frequent mensuration£¨LY-1 apparatus£©have been adopted in testing road.And the detection results about four methods were analyzed and compared.Sand cone method was conducted as a standard method of field detection for compaction degree, other three methods were regressed with sand cone method,and the relationship was obtained. The relevance of cutting ring method with sand cone method is excellent,the relevance of other two methods with sand cone method is slightly bad which may because of the soil and construction methods.But in general, it is approved that sand cone method method which act as the standard one of detection for compaction degree is worthwhile extending.

Abstract: In this study, abrasive wear behaviour of MoB/CoCr coating deposited by low pressure plasma spraying (LPPS) was investigated. The properties of microhardness and bond strength of the MoB/CoCr coatings were tested. The abrasive wear properties were evaluated by MLS-225 wet sand rubber wheel tester. The results show that MoB/CoCr coatings are dense and have excellent mechanical properties with high microhardness (930HV0.2) and bond strength (71MPa). The MoB/CoCr coatings have high abrasive wear resistance property.