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Research on Femtosecond Laser Purse Polishing of Silicon Carbide Ceramic Material

Author: LiWeiBo
Tutor: ZhaoQingLiang
School: Harbin Institute of Technology
Course: Mechanical Manufacturing and Automation
Keywords: Femtosecond laser Silicon carbide Laser polishing Processing mechanism
CLC: TN249
Type: Master's thesis
Year: 2011
Downloads: 68
Quote: 0
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Abstract


Silicon carbide is the second silicon , germanium, arsenic after the development of the third generation of semiconductor material . Than high stiffness , good thermal stability , and has become the material of choice for the production of high precision space mirror , and has great application prospects in the field of space optics and electronics , and micro- structure mold processing . Silicon carbide as a multiphase ceramics have high hardness and brittleness, and is a typical hard to machine materials . How to achieve precise and efficient processing of its surface is a pressing problem . Laser polishing technology only appeared in recent years , a new type of surface processing technology . Especially ultrashort pulse laser polishing , not only the processing of high efficiency and high precision polishing , heat-affected zone is small , very suitable for precision polishing of hard and brittle materials . This article from the polishing system structures , experimental design, experimental implementation such as data analysis and processing system to study the mechanism of femtosecond laser polishing silicon carbide materials and processing process . Femtosecond laser (λ = 800nm, f = 1kHz) polishing silicon carbide by confocal laser microscopy and scanning electron microscopy to detect the polishing surface morphology and surface roughness analysis of the laser pulse energy density , the spot the overlaps rate ( scanning speed , scan span ) , the laser incident femtosecond laser polishing silicon carbide process and polishing quality . First pulse width 50fs, repetition frequency of 1kHz femtosecond laser to silicon carbide ablation threshold experiments were obtained SiC under femtosecond laser ablation threshold 0.23J/cm 2 , the focused spot beam The waist radius of 31μm. Using a scanning electron microscope, the morphology of the ablation spots were observed and analyzed and found that the Gaussian distribution of energy of the laser beam irradiation , ablation spots from the center to the edge to present different ablation morphology . Directional striped micro structure rules of the edge of the ablation spot and along with granular SiO 2 appear . Second , in the air atmosphere using a different laser energy density, the the spot overlap rate , and the laser incident on SiC polishing experiment . Found that when the other parameters remain unchanged , within a certain range , the surface roughness after polishing with the laser energy density increases and decreases ; spot overlap ratio , and increase the laser incident angle , can be obtained a smaller surface roughness .

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CLC: > Industrial Technology > Radio electronics, telecommunications technology > Photonics technology,laser technology > Laser technology, the maser > Laser applications
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