Papers by Keyword: Slurry

Abstract: In order to get a high drilling speed of shaft of nearly 13 m diameter, the authers studied on the shape of the cutter head, particularly about the cone angle. The paper discussed the motion process of slurry of drilling shaft, analysed the forces on the cutter head, and the forces on the cuttings and the motions of the cuttings in slurry. The results show that, the cone angle of the cutter head can be minished at least 20 degree.

Abstract: It is the most effective resource use practices for coal slurry to be used as fuel for fluidized bed boiler. The dry desulfurization of slurry fluidized bed boiler is a large time delay system, and the load disturbance of this system changes frequently. In order to achieve stable control of SO2 emission and meet environmental requirements, a fuzzy control technology combined with the optimal feed-forward was designed. Combined with field experience, a fuzzy controller system was designed by fuzzy control technology, and then the integral process was added to achieve non-error track. To reduce the impact of desulfurizer and other factors, based on the principle of feed-forward, an objective to minimize disturbance impact was obtained, and then a nonlinear programming problem for solving the optimal feed-forward parameters was established, from which the best feed-forward form can be obtained. Results of 440T/H fluidized bed boiler show that the proposed method has satisfactory control effect. SO2 concentration can fully meet environmental emission requirements, and its fluctuation is relatively small.

Abstract: Chemical-mechanical polishing (CMP)-a perspective technology in fabrication of micro-and nanoelectronics elements, devices and systems. The development of models of CMP processes remains to be the actual problem. It is pointed out that known CMP models do not account for the features of chemical and mechanical mechanisms of interaction of active fluid and particles with a polished surface as well as an interaction of a viscoelastic pad with the surface. A description of the elementary acts of such interaction are absent in the available models. On the base of the analytical review of the current state of the theory and problems of (CMP) modeling some approaches were suggested to the problem accounting for the complex of the phenomena of different scales determining the polishing rate such as diffusion of slurry into the surface layer and restriction of time of chemical treatment of the surface by a rough pad being under the action of a mechanical load. A model of the CMP process was developed. Within the framework of this model a dependence of the polishing rate on the loading parameters was derived. The dependence generalizes the empirical Preston law.

Abstract: Slurry formulation and printing process determine resistance and heating properties of HTCC, which directly affect the performance of the product. In this paper, through a large number of experiments , we found when the tungsten powder size in slurry formulation was 1-2μm , the flatness and adhesion of substrate were best , and that printing slurry weight and resistance of HTCC were inversely related. In addition,the printing process,such as printing pressure,the shape and angle of blade had effects on the resistance of HTCC.

Abstract: Zirconia fibers have recently become a research hotspot for their superior physical and chemical properties. In this paper, zirconia slurry was prepared by inorganic salt solution added with zirconia powders, the effect of content of PVA, PEG and zirconia powder solid content of the slurry on properties of slurry was studied. Research shows that: the content of PEG as a dispersing agent was 5wt.%, The dispersibility of zirconia powder and stability of slurry got the best, but slurry viscosity was correspondingly higher. Solid content of zirconia powder had an important impact on the rheological properties of slurry, when zirconia solid content was less than 30%, the slurry showed as a pseudoplastic fluid, whereas the zirconia solid content of slurry became 40% and 50% it exhibited plastic fluid characteristics. Solid content of slurry was 50wt.%, the stability of slurry got the best.

Abstract: Novel, unconventional type of high temperature coating systems can be elaborated by depositing Al micro-particles on nickel base substrates, using an appropriate binder, and converting them into a thermal barrier type coating by a two-step heat treatment under argon. Final result is a coating structure consisting of a quasi-foam top coat, constituted by spherical hollow alumina particles, surmounting a β-NiAl diffusion layer able to form during high-temperature oxidation a protective alumina scale. In this work, pure nickel was employed as a model material to evaluate the effects of moderate temperatures (550-700°C), dwelling times and Al particle size on the final characteristics of the coatings. Almost no diffusion occurred below 600°C. In contrast, a Ni₂Al₃ layer very quickly formed at 650 or 700°C. The rapidity of coating formation was attributed to the appearance of a liquid phase at the coating/substrate interface. The increase of dwelling time did not provide any significant thickness increase as the Al particles got practically emptied after 2h. In addition, the use of different micro-sized particles resulted in similar Al diffusion coatings under the investigated conditions.

Abstract: GaAs are one of the most important semiconductor followed silicon, GaAs wafers are the mostly used substrates for fabricating integrated circuits (ICs). So the quality of ICs depends directly on the quality of GaAs wafers. A series of processes are required to manufacture high quality GaAs wafers. This paper reviews the literature on polishing technology of GaAs wafers, covering the history, summarizes the effects of slurry’s chemical and physical characters such as pH, oxidants, abrasive grit, velocity, and temperature in the polishing process. It also discusses some possible topics for future research.

Abstract: Preparation of aqueous ceramics slurry with high solid volume and low viscosity is premise and key step of gelcasting, and dispersant play important role in slurry preparation. In this paper, triammonium citrate (TAC) was used as dispersant of PMN-PZT piezoelectric ceramics slurry, the effects of TAC on slurry stability and rheological properties and dispersion mechanism of TAC were investigated by sedimentation test, viscosity, scanning electron microscopy (SEM) and FTIR analysis. The SEM results indicated that TAC could reduce the agglomeration of powder particles and make ceramic particles well-dispersed. FTIR indicated that strong chemical absorption occurred between TAC and PMN-PZT powder, and slurry stability and rheological properties of PMN-PZT slurry were improved through electrostatic interaction of TAC. The effects of TAC on sedimentation volume and viscosity have similar tendency. When TAC content was 7.5vol% and pH of slurry was about10, PMN-PZT slurry suitable for gel-casting could be acquired.

Abstract: In current research, a series of visualization experiments simulating the action of ultrasonic vibration (UV) in metal slurry preparation process on fluid flow, grain nucleation and growth as well as its interaction with viscosity of fluids were conducted. In these visualization experiments, the metal slurry maker was substituted by a transparent cup while the liquid and semisolid slurry of metal were replaced by other fluids or mixture system with similar characteristics. Scaled-up UV was applied to the liquid or mixture systems. The simulation shows that UV can roll up the particles at the bottom of the cup and make the liquid convection intense below the radiating surface of sonotrode while weak above it. UV can break dendrites rapidly and distribute them in melt. High viscosity reduces the actual power transmitted into liquid, and higher viscosity requires higher inception power of UV.

Abstract: Microencapsulated phase change material (PCM) slurry is a kind of novel heat transfer fluid called latent functionally thermal fluid. Unlike conventional (sensible) materials, when the PCM reach the temperature at which they begin phase change (its melting point), they absorb large amounts of heat with little or no temperature change. Due to this, the heat transfer ability and energy transport ability can be obviously improved. Therefore, they have many potentially important applications in some fields such as energy storage, thermal conditioning of buildings, waste heat recovery, off peak power utilization, heat pump systems, space applications. In present study, the core materials are encapsulated with membrane of synthetic material. And the core materials are composed of several kinds of n-paraffin waxes (mainly nonadecane) and the membrane is a type of melamine resin. The range of diameter of the PCM particles is distributed from 0 μm to 4.5 μm, and its average diameter is 0.74 μm. The thickness of melamine resin is about 11nm. The melting point of the PCM is about 304K. Physical properties, such as density, diameter and its distribution of microencapsulated PCM slurry are investigated. Meanwhile, the thermal physical property, apparent specific heat, is determined by a Differential Scanning Calorimeter (DSC). Also, the influence of mass concentration has been discussed.