Microwave sintering of Ca<Subscript>0.6</Subscript>La<Subscript>0.2667</Subscript>TiO<Subscript>3</Subscript> microwave dielectric ceramics

Ca_0.6La_0.2667TiO₃ ceramics were prepared by conventional and microwave sintering techniques and their sinterability, microstructure, and microwave dielectric properties were investigated in detail for comparison. Densified Ca_0.6La_0.2667TiO₃ ceramics were obtained by microwave sintering at 1350°C for 30 min and by conventional sintering at 1450°C for 4 h. An unusual phenomenon was found that some larger grains (grain size range: 8–10 μm) inclined to assemble in one area but some smaller ones (grain size range: 2–4 μm) inclined to gather in another area in the microwave sintered ceramics. The microwave dielectric properties of Ca_0.6La_0.2667TiO₃ ceramics prepared by microwave sintering at 1350°C were as follows: dielectric constant (ɛ _r) = 119.6, quality factor (Qf) = 17858.5 GHz, and temperature coefficient of resonant frequency (τ _f) = 155.5 ppm/°C. In contrast, the microwave dielectric properties of the ceramics prepared by conventional sintering at 1450°C were ɛ _r = 117.4, Qf = 13375 GHz, and τ _f = 217.2 ppm/°C.     

盐藻多糖提取及初步纯化

对提取β-胡萝卜素后的杜氏盐藻渣中多糖的提取、初步纯化和多糖脱色方法进行了实验研究.实验采用水浸提的方法,考察了提取温度、提取时间、液固比和pH值对盐藻多糖提取率的影响,盐藻多糖的最适提取条件为:提取温度:70℃,提取时间:4 h,液固比:30:1,pH值10,在此条件下,盐藻多糖的提取率为8.63%,多糖含量为65.73%.采用分级醇沉和分步醇沉的方法沉淀多糖,得到醇沉最佳条件为无水乙醇一步醇沉.采用中性蛋白酶水解脱除盐藻多糖提取液中蛋白质,脱除率为61.55%,脱蛋白后多糖含量为70.96%,采用过氧化氢对脱蛋白后多糖提取液脱色,脱色率为78.66%.     

Applications and research in frame longeron of hydroforming

The application feasibility of hydroforming in frame longeron large parts is verified for the first time at home. The result of the research on the structure design and process analysis for frame longeron shows that hydroforming can be fully realized.With stiffness is comparison,collision test simulation and cross section force with traditional drawingassembly welding techniques,it has been found that hydroforming combining has multiple advantages such as lightweight, high stiffness,reduction in the number of parts,high precision,hence reduction the associated machining and welding and so on.It is especially suitable for forming various lightweight components used for the chassis parts in automotive.     

(G'/G)-展开法与带有Kerr law非线性项的非线性扰动Schrodinger方程的行波解

研究带有Kerr law非线性项的非线性扰动的Schrodinger方程.利用文献[1]中的(G'/G)-展开法,得到其行波解,而且行波解可由双曲线函数、三角函数和有理函数表示.     

高速铁路绝缘轨距块用增强尼龙专用料研究

以尼龙(PA)为基体树脂,通过不同黏度的PA复合,优化选择了具有较好加工性能和机械强度的基体材料。同时,选择不同直径的玻璃纤维,研究玻璃纤维种类和含量对复合材料性能的影响,对比普通玻璃纤维和无碱玻璃纤维对复合材料的耐醇解性能影响,使复合材料具有优异的耐高温性能和较好的耐醇解性能。为了提高抗氧剂的物理损耗性能,制备了纳米二氧化硅表面负载抗氧剂,并采用红外光谱法研究了接枝结构。     

拮抗菌HT-6对致病疫霉的竞争及诱导性抑制

为深入了解细菌HT-6对致病疫霉(Phytophthora infestans)菌丝生长的抑制机理,采用琼脂柱对接法观察细菌HT-6对致病疫霉空间位点的竞争,铬天青(CAS)培养基观察嗜铁素的产生,硫酸-蒽铜比色法和水杨酸浓硫酸比色法分别比较葡萄糖和硝态氮的利用率,同时以致病疫霉及其细胞壁制剂(CWP)为诱导物,采用平板透明圈法观察HT-6产生的纤维素酶和β-1,3-葡聚糖酶,DNS法测定酶活并评价含有2种酶的无菌体发酵液对致病疫霉的抑制活性.结果显示,单独接种在PDA琼脂柱上的致病疫霉能沿琼脂柱生长并迅速扩展至黑麦固体培养基(Rye)表面生长,与致病疫霉菌饼对接的HT-6也能沿着琼脂柱生长并扩展至Rye培养基表面迅速蔓延,而与HT-6对接的致病疫霉菌丝体仅在PDA琼脂柱上生长,没有扩展至Rye表面,被HT-6的生长所阻止;HT-6能产生嗜铁素,致病疫霉不产生嗜铁素;HT-6对葡萄糖和硝态氮的利用率(75.66%和69.05%)均显著高于致病疫霉(55.97%和56.87%);HT-6菌株单独培养时不产生纤维素酶和β-1,3-葡聚糖酶,但致病疫霉菌体和CWP均能诱导HT-6产生这2种酶,其中菌体诱导后的2种酶活,分别为6.638、2.913 U,均显著高于CWP的诱导处理(1.326、1.289 U,P<0.05);CWP诱导后含有2种酶的HT-6无菌体发酵液对致病疫霉菌丝生长具有明显抑制作用(抑菌率为33.25%),但显著低于单独培养的HT-6菌液原液的抑菌活性(抑菌率为81.33%).这表明HT-6能够通过空间和营养竞争以及致病疫霉诱导产生的细胞壁降解酶抑制致病疫霉,其中以空间和营养竞争为主.     

铜转炉烟灰酸浸净化液中锌的萃取分离

以p204为萃取剂,260号磺化煤油为稀释剂,从铜转炉烟灰酸浸净化液中萃取分离锌.考察萃取振荡时间、p204的体积分数、相比率(O/A)以及料液初始pH值对锌萃取率的影响.通过正交实验和单因素分析确定p204从铜转炉烟灰酸浸净化液中萃取分离锌的主要影响因素和最佳工艺条件.研究表明:室温条件下,当萃取平衡时间为6 min,p204的体积分数为30%,相比率(O/A)为2∶1,料液初始pH值为3.0时,锌的一级萃取率达到57.32%.经4级错流萃取可以将料液中锌的质量浓度降低到0.027 g/L,锌萃取率达到97.26%.负载有机相经2 mol/L的H2SO4反萃,锌可完全反萃.     

Hydrogen-induced cracking behaviors of Incoloy alloy 825

The effect of hydrogen on the fracture behaviors of Incoloy alloy 825 was investigated by means of slow strain rate testing (SSRT). Hydrogen was introduced into the sample by electrochemical charging. The results show that surface microcracks form gradually during aging at room temperature when desorption of hydrogen takes place after hydrogen charging at a current density of 5 mA/cm2 for 24 h. SSRT shows that the increase of ductility loss is significantly obvious as the hydrogen charging current density increases. Scanning electron microscopy (SEM) images reveal ductile fracture in the pre-charged sample with low current densities, while the fracture includes small quasi-cleavage regions and tends to be brittle fracture as the hydrogen charging current density increases to 5 mA/cm2.     

Test research on sticking mechanism during hot rolling of SUS 430 ferritic stainless steel

The sticking phenomenon during hot rolling of SUS 430 ferritic stainless steel was investigated by means of a two-disc type high-temperature wear tester. The test results indicate that sticking particles on the surfaces of high chromium steel (HiCr) and high-speed steel (HSS) rolls undergo nucleation, growth, and saturation stages. Grooves on the roll surface generated by grinding provide nucleation sites for sticking particles. The number of sticking particles on the HiCr roll surface is greater than that on the HSS roll surface. The average surface roughnesses (R_a) of HiCr and HSS rolls change from 0.502 and 0.493 μm at the initial stage to 0.837 and 0.530 μm at the saturation stage, respectively. The test further proves that the sticking behavior is strongly dependent on roll materials, and the HSS roll is more beneficial to prevent particles sticking compared with the HiCr roll under the same hot-rolling conditions.     

Precipitation and stability of reversed austenite in 9Ni steel

A new method was used to analyze the factors affecting the precipitation of reversed austenite during tempering. The samples were kept at various tempering temperatures for 10 min and their length changes were recorded. Then, the precipitation of reversed austenite which led to the length reduction was shown by thermal expansion curves. The results show that the effects of process parameters on the precipitation of reversed austenite can be determined more accurately by this method than by X-ray diffraction. When the quenching and tempering process is adopted, both the lower quenching temperature and higher tempering temperature can promote the precipitation of reversed austenite during tempering; and when the quenching, lamellarizing, and tempering process is used, intercritical quenching is considered beneficial to the precipitation of reversed austenite in the subsequent tempering because of Ni segregation during holding at the intercritical temperature.