Papers by Author: Mao Lu Wang

Abstract: Sapphire is an important wide bandgap semiconductor material for developing UV/blue optoelectronic devices, however because of its high hardness and chemical stability; it is mechanically and chemically difficult machine. In this paper, the scribing of sapphire by UV laser pulses is investigated under various conditions of pulse energies, scanning speed and repetition rate. The quality and morphology of the laser ablation of sapphire surface are evaluated by scanning electron microscopy. The mechanism of UV laser ablation of sapphire is discussed. The formation of grooves with high aspect ratio and good surface quality is achieved by selecting appropriate laser parameters. Scribing by pulsed UV laser therefore provide a new approach in the development of sapphire-based devices.

Abstract: The Processing advantages of UV laser were discussed in this paper. A series of experiments were carried out, some good results was achieved, which proved UV laser is fit for sapphire wafer processing. Then how processing parameters affects machining quality was discussed, which provides guidance to machining practice. The formation of grooves with good surface quality can be achieved by selecting appropriate laser parameters.

Abstract: Water-jet guided laser micromachining is the new development of laser machining. This paper analysis the action mechanism of the plasma shock wave and hollow erode effects in water-jet guided laser machining processing, on the base of the thermal effects of the laser and water-jet. And the numerical model on the action effects between the water-jet guided laser and the material was founded. Using the software ANSYS, the processing of the water-jet guided laser micromachining was simulated. This paper gave the investigation on the distributing of temperature field in processing of water-jet guided laser micromachining. And the results of the correlative experiment correspond with the simulation results.

Abstract: An investigation on the mechanism of flexible sheet metal forming using plasma arc have been performed in this paper. The experimental results show that temperature gradient mechanism (TGM) is caused by a steep temperature gradient across the sheet metal thickness, which will generates bending towards the plasma arc, while buckling mechanism (BM) usually causes sheet metals to bend away from the plasma arc on the condition that the plasma arc diameter is large compared to the sheet metal thickness and the scanning speed is low. The strain-hardening effects and phase transformation effects were also conducted in the investigation, which can be of great significance for the micro hardness and deformation of sheet metal in the heated area. The investigation reveals the mechanisms of sheet metal forming using plasma arc, and provides theoretical foundation for its industry application.