Effects of CO2 Laser Surface Processing on Fracture Behavior of Silicon Nitride Ceramic

Surface defects generated by grinding deteriorate the flexural strength of the silicon nitride (Si3N4) ceramic. In this paper, CO2 laser surface processing was applied to eliminate the grinding-induced defects. SEM micrograph showed that the surface integrity of Si3N4 samples was improved after laser processing. Four-point bending tests and fractographic analysis indicated that the flexural strength and fracture origins were affected by the change of surface integrity in laser-treated Si3N4 samples. The effect of grinding-induced residual stress on flexural strength of laser-treated samples was discussed. It was concluded that laser surface processing had significant effects on fracture behavior of flexure Si3N4 samples.

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Fracture Toughness Modifications By Means of CO2 Laser Beam Surface Processing of a Silicon Nitride Engineering Ceramic

Proceedings of the 36th International MATADOR Conference ◽

10.1007/978-1-84996-432-6_114 ◽

2010 ◽

pp. 519-522 ◽

Cited By ~ 1

Author(s):

P. P. Shukla ◽

J. Lawrence

Keyword(s):

Fracture Toughness ◽

Silicon Nitride ◽

Laser Beam ◽

Co2 Laser ◽

Surface Processing ◽

Engineering Ceramic ◽

Beam Surface

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A comparative study on the processing parameters during fibre and CO2 laser surface treatments of silicon nitride engineering ceramic

The International Journal of Advanced Manufacturing Technology ◽

10.1007/s00170-011-3471-7 ◽

2011 ◽

Vol 59 (1-4) ◽

pp. 143-155 ◽

Cited By ~ 4

Author(s):

Pratik P. Shukla ◽

Jonathan Lawrence

Keyword(s):

Silicon Nitride ◽

Comparative Study ◽

Co2 Laser ◽

Processing Parameters ◽

Surface Treatments ◽

Laser Surface ◽

Engineering Ceramic

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Experimental investigation of laser surface processing of flexure silicon nitride ceramic

Transactions of Nonferrous Metals Society of China ◽

10.1016/s1003-6326(06)60256-2 ◽

2006 ◽

Vol 16 ◽

pp. s558-s565 ◽

Cited By ~ 12

Author(s):

Li SUN ◽

A.P. MALSHE ◽

Wen-ping JIANG ◽

P.H. MCCLUSKEY

Keyword(s):

Experimental Investigation ◽

Silicon Nitride ◽

Laser Surface ◽

Surface Processing ◽

Silicon Nitride Ceramic

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Laser-Assisted Surface Engineering of Silicon Nitride to Minimize the Surface Defects Generated During Grinding Operation: Part I

10.1115/imece2000-1903 ◽

2000 ◽

Author(s):

Palaniappan Chinnakaruppan ◽

Ajay P. Malshe ◽

Sharad N. Yedave ◽

Beom Soo Park ◽

William F. Schimdt ◽

...

Keyword(s):

Silicon Nitride ◽

Flexural Strength ◽

Surface Engineering ◽

Surface Defects ◽

Continuous Wave ◽

Research Work ◽

Ground Surface ◽

Scanning Speed ◽

Diamond Wheel ◽

Power Densities

Abstract Silicon Nitride (Si3N4), a structural ceramic, is being increasingly used for various applications such as bearings, rotors, valves, etc., due to its highly useful mechanical and physical properties. To achieve the desired close tolerance and better surface integrity for such applications, abrasive machining using diamond wheel grinding, is primarily used. Due to the extreme mechanical properties of the silicon nitride, sub-surface and surface defects like micro-cavities, micro-cracks, smeared areas and debris are formed on the ground surface of the component due to grinding. The final flexural strength of the components are jeopardized to a greater extent due these surface defects. In this research work, a novel process is developed and established to eliminate/minimize these surface defects. The process involves annealing of defects using continuous wave carbon-dioxide (CW CO2, λ = 10.6μm) laser radiation. The laser is applied as a radiation source to selectively soften and reflow the secondary non-Si3N4 phase material to fill/anneal the defects present in the surface and sub-surface. Experiments were performed at three different power densities and at a constant scanning speed in air ambient. Power densities and scanning speed were selected based on the output of the model. It is found during the investigation that the laser treatment reduces the surface roughness and increases the micro-hardness without any change in the surface stoichiometry. Also, the sub-surface and surface defects are minimized and the flexural strength, which is an important property for the related applications, is found to be increased after treatment. The detrimental influence of machining defects on the mechanical failure of the sample during the four-point bend testing was found to be significantly reduced.

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