Advanced Materials Research Vol. 852

Abstract: in this paper, the automotive interior decoration scrap (FRTPP) have been successfully cut in to certain size tiny lumps via self-designed fully enclosed mechanical shred device. Then this lumps were filled in to the PP with additives by the double screw extrusion. The influences of the lumps sizes on the micro-structures , thermal stability,processing fluidity and mechanical properties of the as-fabricated composites have been systematically investigated. Otherwise the morphology changes of polyester fabric attached to the surface of leftover materials have been investigated at different temperature. The results shows that: the different size lumps were homogenously dispersed in the polymer; The thermal stability and fluidity of composite made by 10mm×10mm lumps is the best. The tensile strength of the product by 15mm×15mm increased by 10% while notched impact strength increased by 22%; The polyester fabric remains fiber structure at the processing temperature (190°C-210°C) and can be used as reinforcements for pp.

Abstract: NiCoW alloy powders with and without 0. 4 % La₂O₃ were flame spray welded onto 1045 carbon steel substrate. Vickers microhardness profiles of the coatings were carried out. Sliding wear tests in dry conditions were carried out by means of weight-loss method for several applications in oil industries. For this purpose, Ni-based alloy and high chrome cast iron were used as compared materials. A scanning electron microscope (SEM) was used to analyze the wear phenomena of samples. The result showed that the hardness of the coatings can be improved by addition of 0. 4 % La₂O₃, and the anti-adhesion, anti-scratching, and plastic deformation resistance abilities of coatings are increased with the addition of La₂O₃.

Abstract: In this study, the effect of pre-wetting super-light aggregate on the microstructure of the aerated concrete was discussed. The experimental results show that: using Scanning electron microscopy to magnify the interface between mortar and aggregate in aerated concrete to 200 times their normal size, the pro-wet treatment densifies the interface,and to 20000 times,fibrous CSH gel and lamellar tobermorite interweave each other and form very pre-pressing structure on the surfaces .

Abstract: This paper mainly studied the effect of niobium on graphite which was quantitatively analyzed by the image analysis software. The results showed that with the amount of niobium increasing the number of nodular graphite and the percent of spheroidization in ductile iron were reduced whereas the size of nodular graphite was increased.

Abstract: Residual stresses were investigation by Three-D finite element simulation and experimental method. The Three-D finite element simulation confirms large residual stress appears in seam zone because of the crack part and the maximum loading parts were not coinciding. The heating/cooling rate can seriously affect the residual stress. Along with the heating rate decrease, the residual stress reduces in material and had big drop in high heating rate range than lower range. And cooling rate influence the residual stress in cemented carbide was more sensitive than in steel. Meanwhile, far away the seam, the residual stress decrease and became stable. After heat treatment, the residual stress reduced from more than 800MPa, 300MPa to less 100MPa, 52Mpa in WC-Co side and steel side respectively and the material had better abrasion resistance and high strength.

Abstract: Nowadays, a large quantity of cemented carbide is being consumed, and the amount of scrap cemented carbide is increasing year by year. In this paper, crystal morphology, element content and phase structure of the recycled cobalt powder as well as recycled tungsten carbide powder were characterized by SEM, EDS and XRD. Hardness of the prepared W-Co alloy using recycled cobalt powder and recycled tungsten carbide powder as the raw materials was tested by Rockwell apparatus. Through analysis of these results, the existing problems in recycling of scrap cemented carbide emerged. As for recycling of scrap cemented carbide, the research results can provide theoretical basis for improvement of recycling technology and process control technology.

Abstract: The 304 austenite stainless steel and low carbon steel clad plate was fabricated by casting and hot rolling process. The mechanical properties and interface shear strength of clad plates with different thickness after rolling were investigated in detail. The microstructure characteristics of the clad interface were observed by SEM (Scanning Electron Microscope). The phases and chemical composition were analyzed by XRD (X-ray diffraction) and EDS (energy dispersive spectroscopy). Based on the results, the mechanical properties and interface shear strengths meet the requirements of national standards. No visible cracks were observed in the clad interface after bending test. Cr₃C₂ precipitates, Fe₃O₄ oxides and Fe-Cr intermetallic compound were distributed around the interface of clad plate after casting, but a good metallurgical bonding was achieved after hot-rolling.

Abstract: The variation of the main strengthening phase MgZn₂ of Mg-Zn-Cu alloy amount and crystallization temperature with Zn and Cu content were studied by thermodynamic calculation using FactSage software and magnesium alloy database, and according to the thermodynamic optimization results we melted Mg-6Zn-1.5Cu.We researched the structure of the experimental alloy as-cast after peak aging at 160 °Caging by TEM, XRD and DSC. The results showed that the experimental alloy aged at 160 °C was about 15% higher than Mg-6Zn binary alloy, and peak aging organization's main strengthening phase is more evenly distributed, the higher density of -MgZn₂ phase. Cu is added to improve the phenomenon of the Mg-Zn binary alloy aged structure distribution uneven precipitation of low density as well as easy to averaging.

Abstract: The mixture powder of Cr, Ni, Mo and Cu were deposited evenly on a ductile iron with ferrite matrix and treated by plasma transferred arc (PTA). The microstructure and hardness distribution of the PTA-alloyed layers were investigated by using scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and microhardness tester, respectively. Results show that the cross-section consists of four regions: alloyed zone, melted zone, heat affected zone and unaffected substrate. The maximum microhardness of PTA-alloyed sample is measured to be as high as 1077 HV_0.2, which is approximately 4.4 times higher than that of substrate. The improvement is attributed to the formation of mixed hard-phases such as Cr₇C₃, C₂₃C₆, martensite, cementite under nonequilibrium solidification, and the solution strengthening by the alloying elements as well as grain refining via the rapid cooling.

Abstract: Interfacial atomic structure of iron and transitional metal carbides interface systems were investigated by first-principle method. Meanwhile, free surfaces of iron and transition metal carbides were also researched, and systematically analyzed the differences of atomic moving behaviors of two interfacial systems. These calculations indicated that the atomic movements of transitional metal carbides were lesser than softer iron matrix in these interfacial systems.