Papers by Author: Miao Qian

Abstract: In order to carry out reaction smoothly, a measure and control system of an onboard micro-channel reactor for hydrogen production via methanol steam reforming is developed. A subsystem of temperature control is designed to measure and control the temperatures of reactor and evaporator. Flow control subsystem, including liquid flow control of reactant and mass flow control of reducing gas, is also developed. Virtual instrument technology and graphical programming language LabVIEW are applied to integrate all the control functions in a single program, which makes it convenient for operation and further development. The experimental results validate that the reaction can be carried out successfully under the control of this measure and control system.

Abstract: This paper analyzes the property parameters influences of semi-fixed abrasive plate on the ‘trap’ effect with discrete element simulation by Particle Flow Code (PFC). The effects of the property parameters such as porosity, hardness and size of the abrasive particles, friction coefficient between the abrasive particles and the bonding agent concentration are simulated. The simulation results show that porosity, friction coefficient, bonding agent concentration has great influences on the ‘trap’ effect, while hardness and size of the abrasive particles almost have no effect. Grey incidence analysis is carried to determine the influence degree of porosity, friction coefficient, bonding agent concentration, and the results show that the most important factor is the porosity, followed by the friction coefficient, and then the bonding agent concentration.

Abstract: This work aims to obtain fine surface of silicon wafer during precision and ultra precision machining, and presents a new method called semibonded abrasive machining. A semibonded abrasive grinding plate is used in the semibonded abrasive machining. Abrasive particle of 1000# Green SiC and bond named SSB are adopted in the manufacture of the plate. Four plates with different concentration of bond which are 1.5%, 2.5%, 3.5%, 4.5% respectively are made. The paper studies the effect of concentration of bond, the control parameters which include the lapping time, the load, and the rotating velocity of the plate on the surface roughness. Experimental results indicate each plate with different concentration of bond can obtain fine surface roughness. When the load or the rotating velocity increases, there is little effect on the surface roughness, but the material removal rate increases correspondingly. The initial roughness of the silicon wafer surface lapping by the plate could be improved from Ra 0.2μm to Ra 0.02μm in 9 min.

Abstract: The semibonded abrasive machining technique is expected to get high surface integrity and processing efficiency attributed to the „trap‟ effect which can reduce or even eliminate the surface damage induced by the larger particles. The goal of the work is to validate the „trap‟ effect by the experiments of semibonded and loose abrasive machining under the conditions of adding and not adding the larger particles. Free surface damage monocrystal silicon wafers after polishing are adopted as workpieces, and 1000# SiC as abrasive particles while 180# SiC as the larger particles. The cast iron plate is used as grinding plate in the loose abrasive machining and different bond concentration semibonded abrasive grinding plate SSB-1 and SSB-2 are used as grinding plates in semibonded abrasive machining. The roughness Rv and SEM photos of workpieces surface are tested to evaluate the extent of „trap‟ effect. The result shows that the semibonded abrasive grinding plate has the „trap‟ effect. The shore hardness value of the semibonded abrasive grinding plate can be used to be one parameter to evaluate the degree of the ‟trap‟ effect of the semibonded abrasive grinding plate.