Advanced Materials Research Vols. 295-297

Abstract: A TiC whisker toughening Al₂O₃-based ceramic cutting tool composite named ATW30 was developed by a two-step in situ synthesis technology. The fracture toughness, flexure strength and Vickers hardness of the composite were 7.63MPa•m^1/2, 800MPa and 19.5GPa, respectively. Compared to a (W, Ti)C particle strengthening Al₂O₃-based ceramic cutting tool composite named SG4, ATW30 was with lower flexure strength and Vickers hardness but much higher flexure strength, and therefore obviously higher wear resistance at either lower or higher cutting speed. The dominant wear mechanism on the flank face of ATW30 is abrasive wear at lower cutting speed and adhesive wear at higher cutting speed. Because of the appearance of the adhesive wear, the wear resistance of ATW30 at higher cutting speed is lower than that of itself at lower cutting speed.

Abstract: In this paper, Poly(lactide-co-glycolide) (PGLA) fibers were treated with the plasma. The surface, tensile strength, and contact angle with water of the PGLA fiber were investigated. The results showed that the PGLA fiber after treatment possessed more rough surface and smaller contact angle with water compared with the untreated fiber, but the tensile strength of fiber after treatment was not significantly diffrent form the fiber before treatment. In addition, both the treated and untreated PGA fibers were placed in phosphate buffer solution (PBS) (pH=7.4) at 37 °C up to 2.5 weeks to investigate the effect of plasma treatment on the degradation in vitro. Changes in tensile strength during degradation was investigated. The results showed that the treated PGLA fiber degraded faster compared with the untreated fiber.

Abstract: In order to find the relationship between tensile sample laminations and inner quality of Q345 slabs, casting trials in conditions of with and without EMS and different superheating have been carried out. It is found that slab inner quality can be improved a lot with EMS, center equiaxial grain ratio increases greatly. Lowering superheating leads to downgrading of center deviation, however, center equiaxial grain ratio increases not too much compared with EMS. Tensile samples produced by above-mentioned measures do not break in the center area.

Abstract: The high efficient, high reliability and energy-saving development of modern machinery equipments challenges the higher request for hydraulic sealing technology. However, current seal designer usually operates on the basis of his experience and skill, without systemic design theories and methods as guides. In this paper, according to the work principle of elastomeric hydraulic reciprocating sealing, the seal efficiency reinforcement design theory such as seal efficiency-reinforcement design rules and the seal failure criterion are proposed based on the numerable model and finite element analysis methods. This theory can offer theorical methods guider for seal design, so as to satisfy modern machinery equipments request for higher effciency and environment protest.

Abstract: In this study, microwave heating was used for the preparation of stearate-carboxymethyl konjac glucomannan ester (SCMK), which introduced hydrophilic carboxymethyl and hydrophobic stearate groups on konjac glucomannan (KMG) backbone. The physico-chemical properties and structure of SCMK were investigated. Results show that the viscosity of SCMK is much lower than that of KGM, but larger slightly than the carboxymethyl konjac glucomannan (CMK) and the viscosity is still stable after being placed for 48 h at ambient temperature. Its transmittance decreases and the resistance ability of SCMK solution to salt/sugar as well as base have been significantly promoted. Moreover, SCMK with substitution degree (DS) of 0.02 is proved to be a sound oil/water emulsifier which its HLB value is 13.01. In FTIR spectrum, the absorption peak of SCMK decreases at 2161.84 cm^-1 and 2360.74 cm^-1. Meanwhile, TGA indicates that SCMK is less thermal stable than KGM and CMK, but is still good.

Abstract: The solid solutions of NdFeO₃-Bi₂SrNb₂O9 (1:1ratio) of the Aurivillius-type compounds was prepared by solid-state reaction. The room structural data were obtained from X-ray diffraction (XRD) and confirmed a Three-layered Aurivillius phase. The dielectric measurement showed no anomalies due to the high conductivity of these samples at elevated temperature. From the magnetic measurement the compounds were found to be of canted antiferromagnetic at room temperature. It is revealed that the formation of Fe²⁺ can be suppressed by the pre-oxidation of Fe₂O₃，This result may have implications for further studies on leakage current control of these materials. In all, we’ve synthesized a new material that is ferroelectromagnetic in nature.

Abstract: To study the gelatinization pressures of different kinds of starch at atmospheric temperature, eight different starches chosen as raw materials for this paper (5%w/w, at 20°C) by different pressure were treated, then analysed the relations between pressure and starch gelatinization by X-ray diffraction. The study showed that the gelatinization pressure range of different starches respectively in this experiment was: corn starch (~450 - ~550MPa), wheat starch (~ 450 - ~500MPa), tapioca starch (>450 - ~500MPa), water chestnut starch (>500 - ~550MPa), glutinous rice starch (>500 - ~550MPa), waxy wheat starch (~500 - ~550MPa), waxy maize starch (~550 - ~650MPa), potato starch (~700 - ~750MPa).

Abstract: Spherical tungsten powders were synthesized by (RF) argon plasma with irregular tungsten powders in this paper. The microstructure and crystallographic phases of the synthesized powders were characterized using scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The results showed that fine spherical powder composed of pure tungsten phase with favorable dispersity and its surface becomes smooth. The spheroidization efficiency of synthesized powders was almost 100 %, and the particle size distribution became narrower after spheroidization treatment. The spheroidization efficiency of the sample decreases gradually as increasing of the feeding rate. The RF plasma spheroidization of tungsten powder is an ideal route synthesis of well- spherical metallic tungsten powders which is widely used in thermal spraying and metal injection moulding process.

Abstract: In this work, carbon nanotubes(CNT) filled polyetheretherketone (PEEK), with CNT contents ranging from 1 to 5 vol.%, were compounded by a ball milling process performed under room temperature. Nanocomposites were prepared through compression molding as-milled CNT/PEEK mixtures without further melt mixing. The incorporation of CNT leads to a significant improvement in material stiffness and a decrease in material ductility. The wear resistance of PEEK is significantly improved after incorporating CNT and at a rather low CNT loading, i.e. 5 vol.%, the composite presents the optimum wear resistance.

Abstract: Crystal structure and magnetostrictive properties of Tb_0.2Pr_0.8(Fe_0.4Co_0.6)_1.9B_x alloys have been investigated by means of x-ray diffraction and a standard strain technique. The matrix of Tb_0.2Pr_0.8(Fe_0.4Co_0.6)_1.9 alloy consists of (Tb,Pr)(Fe,Co)₂ phase with a cubic MgCu₂-type structure and some amount of (Tb,Pr)(Fe,Co)₃ phase with a PuNi₃-type structure. The introduction of boron effectively restrains the emergence of the iron-rich phase, which can occupy either the substitutional or interstitial site in this alloy system. The single Laves phase can be obtained for the high Pr-content Tb_0.2Pr_0.8(Fe_0.4Co_0.6)_1.9B_x alloys with 0.05< x ≤0.15, which have improved magnetostrictive properties as compared to the boron free material.