Two kinds of modified amorphous silica, grafted vinyl trimethoxysilane and N-(n-butyl)-3-aminopropyl trimethoxysilane (DYNASYLAN 1189), were obtained from oil shale residue by the technical process of calcination and activation, alkaline dissolution, homogeneous sedimentation with ethylacetate and modification with silane coupling agents.The number of surface hydroxyl groups, modification degree, the structure and other properties of amorphous silica were investigated by chemical method, infrared analysis, nuclear magnetic resonance analysis, X-ray diffraction and scanning electron microscopy.The results show that amorphous silica treated with coupling agents AH-171 and DYNASYLAN 1189 is characterized by modification degrees of surface hydroxyl groups 93.7% and 71.2% and hydrophobic degrees 98% and 94%, respectively, as well as also by improved dispersion in organic solutions.This work gives a valid method to prepare surface modified amorphous silica from the oil shale residue.
For some special structure parts, single casting method cannot reach the product's performance requirements. Because of parts structure limit, in many cases, single free forging is also very difficult. But using the method of casting blank plus free forging to improve its as-cast microstructure, can finish complex or special structure parts manufacturing, among them, the responding tool is another key to solve the problem.
In design and manufacturing of power MOS microelectronic device, deep trench process is used for some special request. The trench depth reaches to scores of micrometer. some are often used in deep trench etching step. Wafer edge generates silicon grass defect. It becomes the major source of particle during the post wet clean steps, which impact line yield and contaminate wet etching tools. The paper introduces two solutions for solving this defect by optimizing trench-photo process. One is inverted trapezoid process and the other is negative resist process. Both solutions in lithography are aimed at wafer edge protection. The deep trench etching step is to protect the underground material from being damaged, and results to solve the wafer edge silicon grass defect of deep trench process.
The drawing of a stainless steel truckfest part was stated.By adjusting the clearance between punch and die plate,and by using new lubricant and lubricating means,the truckfest part can be drawn in good surface quality under the condition of no heat treatment or with different heat treatment process.
Aretractable roof structure is a new type of structure in which part of,or all of the entire roof can be moved or retracted within a short period of time so that the building can be used with the roof both in an open state or in a closed state.In the process of engineering design,it is an important problem of how to design mechanical system.A structure with a retractable roof has many parts whose features are different from those of conventional immobile structures.In fact,the issues cannot be handled by standards for mechanical design to ensure the safety and serviceability of such structural systems.This paper is presented in which derived from the experiences of the actual examples are introduced,such as the current status of the retractable roof systems in each retraction method.It contains some design concepts,general guidelines or mechanical design along with some driving methods of retractable roof structures.It gives some actual examples of retractable roofs with outlines of some relevant design standards and some safety measures.
Different residues of Huadian oil shale processing were investigated. Their inorganic chemical composition and phase structural characteristics were identified by X-ray fluorescence spectrometry (XRF) and X-ray diffractometry (XRD). The influence of calcination conditions on processing residues at different ash activation degrees and impurities' leaching rates as well as the quality of obtained SiO 2 concentrate were investigated by a single-factor method. The results showed that only circular crossflow-type retortingderived semicoke has different phase-structural characteristics at different calcination temperatures. In the range of 700–800 °C , the leaching rate of aluminum and iron reaches the maximum. To prepare SiO 2 concentrate, starting material should be calcined for 1.5 h at 700–800 °C. As a result, SiO2 concentrate which meets the national standard of silica white will be obtained; the content of SiO 2 is 92.34% and its specific surface area 104 m 2 /g. Phase structures of Fushun-type retorting residue and cogeneration power plant ash did not change dramatically at different calcination temperatures. The leaching rate of Al and Fe reached the maximum. Further calcination is unnecessary in reutilization, only removal of impurities by means of acid soaker is relevant. Fushun-type retorting residue can also be used to make SiO2 concentrate which meets the national standard; the content of SiO2 is 90.38%, its specific surface area is 91 m 2 /g. The leaching rate of aluminum from cogeneration power plant ash is lower, and this ash cannot be used to prepare silica white meeting the national standard. It can be applied as an ingredient of cement, at brick preparation, etc. Separation and purification products are a mixture of crystalline SiO 2 and amorphous SiO2, while the content of crystalline SiO 2 is 32.2%.
The characteristics that directional rupture controlled blasting enable directional accumulation of explosive blasting energy are analyzed, and the application of the technology in the cutting blasting is presented. Based on model test in the laboratory and site test, a blasting effect is achieved.
Thick metal plate blanking process on free forging hammer and the forging die construction are introduced together with the method in solving intensive blade wear when small blade clearance is applied. A lubricant formulation to reduce wear and prolong die life is developed. Punch dies on free forging hammer is designed, which expands the applied field of free forging equipment, and solves manufacturing problem without heavy-duty press.
This work adopted 1,10-phenanthroline spectrophotometric method, complexometric titration and X-ray diffractometer (XRD) to investigate active state of aluminum and iron impurities in semicoke of Huadian oil shale which was calcinated at different temperatures and the influence of calcination temperature on leaching rate of impurities (Al, Fe) with acid.The results show that after calcination of semicoke of Huadian oil shale at 700-800 °C, iron and aluminium exist in their maximum active state and turn into materials soluble in acids, which results in their maximum leaching rate.This process is important for the removal of impurities at preparation of high-quality amorphous silica from oil shale ash.
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