The Effect of Slurry Composition and Flatness on Sub-Surface Damage and Removal in Chemical Mechanical Polishing of 6H-SiC

2009 ◽  
Vol 615-617 ◽  
pp. 605-608 ◽  
Author(s):  
Gi Sub Lee ◽  
Hyun Hee Hwang ◽  
Chang Hyun Son ◽  
Jung Woo Choi ◽  
Won Jae Lee ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Removal Rate ◽  
Diamond Particle ◽  
Surface Damage ◽  
Surface Damages ◽  
The Mean ◽  
Sic Wafer ◽  
Slurry Composition ◽  
Nano Size ◽  
Evaluation Parameters

The effect of slurry composition and wafer flatness on a material removal rate (MRR) and resulting surface roughness which are evaluation parameters to determine the CMP characteristics of the on-axis 6H-SiC substrate were systematically investigated. 10 x 10 mm2 6H-SiC substrates and 2-inch SiC wafers fabricated from the ingot grown by a conventional physical vapor transport (PVT) method are used for this study. The SiC substrate after the CMP process using slurry added oxidizers into slurry consisted of KOH-based colloidal silica and nano-size diamond particle exhibited the significant MRR value and a fine surface without any surface damages. SiC wafers having high bow value after the CMP process exhibited large variation in surface roughness value compared to wafer with low bow value. The CMP-processed SiC wafer having a low bow value of 10m was observed to result in the MRR value of 0.15 m/h and the mean height (Ra) value of 0.772Ǻ.

Optimization of Coated SiC Belt Grinding of Alumina Ceramics

2009 ◽  
Vol 76-78 ◽  
pp. 38-42 ◽  
Author(s):  
Xavier Kennedy ◽  
S. Gowri
Keyword(s):  
Surface Roughness ◽  
Material Removal ◽  
High Hardness ◽  
Surface Damage ◽  
High Temperature Strength ◽  
Structural Ceramics ◽  
Alumina Ceramics ◽  
Belt Grinding ◽  
Grinding Parameters ◽  
Surface Damages

Advanced structural ceramics have been increasingly used in automotive, aerospace, military, medical and other applications due to their high temperature strength, low density, thermal and chemical stability. However, the Grinding of advanced ceramics such as alumina is difficult due to its low fracture toughness and sensitivity to cracking, high hardness and brittleness. In this paper, surface integrity and material removal mechanisms of Alumina ceramics ground with SiC abrasive belts, have been investigated. The surface damage have been studied with scanning electron microscope (SEM). The significance of grinding parameters on the responses was evaluated using Signal to Noise ratios.This research links the surface roughness and surface damages to grinding parameters. The optimum levels for maximum material removal and surface roughness been discussed.

Effects of temperature and loads on hardness and surface failure modes of cemented carbide

2020 ◽  
pp. 095440622095251
Author(s):  
Ben Wang ◽  
Tianxu Hao ◽  
Quanwei Yang ◽  
Minghai Wang ◽  
Yaohui Zheng
Keyword(s):  
Failure Modes ◽  
Indentation Test ◽  
Surface Damage ◽  
Mean Free Path ◽  
Cemented Carbide ◽  
Surface Failure ◽  
Binding Phase ◽  
Surface Damages ◽  
The Mean ◽  
Effects Of Temperature

Cemented carbide is a common cutting material with a hardness that significantly affects its usability. A Vickers indentation test was performed to analyse changes in the hardness of cemented carbide cutters with temperature and loads to understand its variation law. Moreover, indentation-induced surface damage was observed, and its elements were analysed. Crack distributions on the indentation surface were detected and analysed through an etching method. The results demonstrate that the hardness of cemented carbide decreases with greater temperatures and loads. At room temperature, the hardness of cemented carbide decreased from 1321 to 996 MPa when the loads increased from 300 to 800 N. When the external load was fixed at 500 N, the hardness of the cemented carbide decreased from 1113 to 939 MPa as the temperature increased from 25 to 350 °C. Moreover, the density of the indentation-induced surface damages increased with a reduction of the Vickers hardness. In addition, the mean free path of the binding phase for the cemented carbide with large grain sizes was relatively high. Therefore, it is difficult to generate diagonal cracks under large loads and high temperatures, which are beneficial to prevent cutter flaking.

Diamond Coated End Mills in Machining Silicon Carbide

2012 ◽  
Vol 576 ◽  
pp. 531-534 ◽  
Author(s):  
Mohamed Konneh ◽  
Mohammad Iqbal ◽  
Nik Mohd Azwan Faiz
Keyword(s):  
Surface Roughness ◽  
Silicon Carbide ◽  
High Performance ◽  
Removal Rate ◽  
Roughness Parameter ◽  
Surface Damage ◽  
Ceramic Materials ◽  
Real Problem ◽  
Machining Parameters ◽  
Machining Processes

Silicon Carbide (SiC) is a type of ceramic that belongs to the class of hard and brittle material. Machining of ceramic materials can result in surface alterations including rough surface, cracks, subsurface damage and residual stresses. Efficient milling of high performance ceramic involves the selection of appropriate operating parameters to maximize the material removal rate (MRR) while maintaining the low surface finish and limiting surface damage. SiC being a ceramic material, its machining poses a real problem due to its low fracture toughness, making it very sensitive to crack. The paper discusses milling of silicon carbide using diamond coated end mill under different machining conditions in order to determine the surface roughness parameter, Rt after the machining processes and to establish a relationship between the machining parameters and response variables. Based on the surface roughness carried out the lowest Rt obtained is 0.46 µm.

EDM Properties of EC-PCD Using a Copper Electrode

2010 ◽  
Vol 126-128 ◽  
pp. 521-526 ◽  
Author(s):  
Shinichi Ninomiya ◽  
Manabu Iwai ◽  
Gaku Sugino ◽  
Takuya Takada ◽  
Kiyoshi Suzuki
Keyword(s):  
Surface Roughness ◽  
Material Removal ◽  
Removal Rate ◽  
Diamond Particle ◽  
Copper Electrode ◽  
Electrically Conductive ◽  
Rotating Electrode ◽  
Single Discharge ◽  
Composite Diamond ◽  
Excellent Tool

Electrically conductive polycrystalline composite diamond (EC-PCD), which consists of electrically conductive diamond grits, has recently been developed for the purpose of providing the material with both excellent tool property and good machinability. This paper deals with an investigation of machinability of EC-PCD by EDM with a copper (Cu) electrode. As a result, it was found that the EDM speed (Material removal rate) for EC-PCD was higher than that of the standard PCD. Although the surface roughness of the standard PCD was 13µm Rzjis at set current ip=3A, the surface roughness of the EC-PCD was 5µm Rzjis at the same current condition. Furthermore, it was observed that the EC diamond particle in EC-PCD was machined by single discharge EDM. Moreover, it was confirmed that EC-PCD was able to be applied a fine discharge profiling or a making fine holes using a rotating electrode.

scholarly journals Study on Improving the Precise Machinability of Single Crystal SiC by an Ultrasonic-Assisted Hybrid Process

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7320
Author(s):  
Dong Shi ◽  
Tianchen Zhao ◽  
Tengfei Ma ◽  
Jinping Pan
Keyword(s):  
Single Crystal ◽  
High Efficiency ◽  
Surface Defects ◽  
Removal Rate ◽  
Oxide Semiconductor ◽  
Hybrid Process ◽  
Ultrasonic Assisted ◽  
Single Crystal Sic ◽  
Surface Damages ◽  
Sic Wafer

Silicon carbide (SiC) devices have become one of the key research directions in the field of power electronics. However, due to the limitation of the SiC wafer growth process and processing capacity, SiC devices, such as SiC MOSFET (Metal-oxide-semiconductor Field-effect Transistor), are facing the problems of high cost and unsatisfied performance. To improve the precise machinability of single-crystal SiC wafer, this paper proposed a new hybrid process. Firstly, we developed an ultrasonic vibration-assisted device, by which ultrasonic-assisted lapping and ultrasonic-assisted CMP (chemical mechanical polishing) for SiC wafer were fulfilled. Secondly, a novel three-step ultrasonic-assisted precise machining route was proposed. In the first step, ultrasonic lapping using a cast iron disc was conducted, which quickly removed large surface damages with a high MRR (material removal rate) of 10.93 μm/min. In the second step, ultrasonic lapping using a copper disc was conducted, which reduced the residual surface defects with a high MRR of 6.11 μm/min. In the third step, ultrasonic CMP using a polyurethane pad was conducted, which achieved a smooth and less damaged surface with an MRR of 1.44 μm/h. These results suggest that the ultrasonic-assisted hybrid process can improve the precise machinability of SiC, which will hopefully achieve high-efficiency and ultra-precision machining.

Research on the Decoating Effect and Microstructure of Surface Damage of High-Pressure Waterjet

2014 ◽  
Vol 541-542 ◽  
pp. 180-184
Author(s):  
Qi Guo ◽  
Xiu Jie Jia ◽  
Shuo Li ◽  
Yan Yan Nie ◽  
Shun Xin Ge
Keyword(s):  
Surface Roughness ◽  
High Pressure ◽  
Impact Test ◽  
Surface Damage ◽  
Water Jet ◽  
Surface Damages ◽  
Pressure Water ◽  
High Pressure Water Jet ◽  
Coated Surfaces ◽  
The Impact

The high-pressure water jet is utilized to perform impact test on coated surfaces with different hardness. The decoating effect is measured and the surface roughness change can be tested by White-light Interferometer (WLI). Also the microstructure of surface damage after impact test is analyzed. The result shows that when utilizing high-pressure water jet to clean the coating, it’s a better choice to start at the place where the coating is broken. The gap will be enlarged rapidly and the decoating velocity will increase linearly. Otherwise, the impact of water jet will cause surface damages and generate holes of particular shape. This kind of hole is flat in the middle, then forming a sunken district and apophysis successively along the radius outwards.

Effect of Abrasives on the Lapping Performance of 6H-SiC Single Crystal Wafer

2013 ◽  
Vol 690-693 ◽  
pp. 2179-2184 ◽  
Author(s):  
Wei Li ◽  
Qiu Sheng Yan ◽  
Jia Bin Lu ◽  
Ji Sheng Pan
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Single Crystal ◽  
Material Removal Rate ◽  
Material Removal ◽  
High Efficiency ◽  
Removal Rate ◽  
Lower Surface ◽  
Crystal Wafer ◽  
Sic Wafer

In order to remove the cutting marks on the cutting surface of 6H-SiC single crystal wafer, experiments were conducted to investigate the effect of the abrasive characteristics (types, grain size, concentration and mixed abrasives) on the lapping performance of 6H-SiC single crystal wafer, then the removal mechanism of the abrasive grains in the lapping process was studied. Results indicate that the abrasives with larger grain size and higher hardness can result in a higher material removal rate while the abrasives with smaller grain size and lower hardness can achieve a lower surface roughness value. When the concentration of the abrasives is 7.69 wt%, a good lapping effect was obtained. Lower surface roughness value Ra can be obtained with a high material removal rate by using certain proportion mixed abrasives. Selecting appropriate abrasives can obtain a high surface quality of 6H-SiC wafer with a high efficiency.

Modeling and Analysis of the Grinding Parameters

2011 ◽  
Vol 110-116 ◽  
pp. 2548-2553
Author(s):  
Priya S. Shinde
Keyword(s):  
Surface Roughness ◽  
Removal Rate ◽  
Surface Force ◽  
Surface Damage ◽  
Mathematical Statistics ◽  
Depth Of Cut ◽  
Functional Requirements ◽  
Modeling And Analysis ◽  
Grinding Parameters ◽  
Grinding Conditions

Efficient grinding of structural ceramics requires judicious selection of operating parameters to maximize removal rate while controlling surface integrity. Grinding of ceramics is difficult because of its low fracture toughness, making it very sensitive to cracking. In the present work, experiments were carried out to study the effect of wheel parameters such as grain size and grinding parameters like depth of cut and feed rate on the surface roughness and surface damage. The significance of the grinding parameters on the selected responses is evaluated using analysis of variance. Mathematical statistics like “Minitab” is used to analyzed the grinding conditions for maximum material removal, using a multi-objective function model, by imposing surface roughness, surface force and surface damage constraints. The choice of including manufacturer & apposes constraints on the basis of functional requirements of the component for maximizing the production rate is also embedded in the Mathematical statistics. For the verification of present work, the Mathematical statistics results are compared with experimental work.

scholarly journals The Effect of Ultrasonic Scaling and Air-Powder Polishing on the Roughness of the Enamel, Three Different Nanocomposites, and Composite/Enamel and Composite/Cementum Interfaces

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3072
Author(s):  
Ksenia Babina ◽  
Maria Polyakova ◽  
Inna Sokhova ◽  
Vladlena Doroshina ◽  
Marianna Arakelyan ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Repeated Measures ◽  
Composite Resin ◽  
Surface Damage ◽  
Third Molars ◽  
Class V ◽  
Composite Surface ◽  
Repeated Measures Anova ◽  
Before And After ◽  
The Mean

We aimed to assess the effects of ultrasonic scaling and air-powder polishing on the roughness of enamel, three nanocomposites (Premise, Herculite Ultra, Harmonize), and composite/enamel and composite/cementum interfaces. Class V cavities were restored in 99 extracted third molars with one of the three nanocomposites and treated with ultrasonic scaler or air-powder polishing device (calcium carbonate or sodium bicarbonate powders). The roughness (Ra) of the investigated surfaces was measured with contact profilometer before and after treatment. The data were analyzed using repeated measures ANOVA. Specimens’ Ra values before instrumentation were near the clinically acceptable 0.2 μm threshold. All techniques increased the roughness of the tested surfaces; however, the enamel was slightly affected. The mean Ra values after prophylaxis for composite, composite/cementum and composite/enamel surfaces were 0.32–0.55, 1.33–1.73, and 1.25–1.36, respectively. The extent of composite surface damage was material dependent. Premise surface was not altered by ultrasonic scaling significantly. Air-powder polishing with both powders produced a greater increase in surface roughness of composite resin and restorations margins than ultrasonic scaling. The Ra values after both types of air polishing for Herculite Ultra and Harmonize were approximately 1.5 and 2 times higher, respectively, than those after ultrasonic scaling (p < 0.05).

Annealing Study of Ga Implanted p-Type 6H-SiC for Ohmic Contact Metallizations

2000 ◽  
Vol 640 ◽  
Author(s):  
M. Prenatt ◽  
A. A. Iliadis ◽  
R. D. Vispute ◽  
M. C. Wood ◽  
M. Derenge ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Contact Resistance ◽  
Ohmic Contact ◽  
Annealing Temperature ◽  
Surface Damage ◽  
Capping Layer ◽  
Force Microscopy ◽  
Annealing Study ◽  
P Type ◽  
Sic Wafer

ABSTRACTShallow implantations of Ga ions were performed on p-type 6H-SiC by conventional broad area implantation, and the physical and electrical properties of the Ga-SiC system upon high temperature annealing were examined, in order to understand the role of Ga in ohmic contact formation. The shallow implantation depth (30 nm) and high Ga doses ranging between 1×1015 and 1×1016 cm−2, resulted in heavy surface damage as observed by atomic force microscopy surveys. Samples annealed using a sacrificial SiC wafer as a capping layer, showed no improvement in surface roughness for annealing up to 1300 °C, while at 1500 °C, surface roughness was markedly changed. At 1600 °C the surface re-crystallized back to the stepped terraced morphology of the un-implanted surface but with significantly larger step and terrace size. At this annealing temperature, heavy Ga loss from the surface was observed. Samples annealed at 1500 °C using an AlN capping layer, showed significant outdiffusion of Si into the AlN layer, and redistribution of Ga within the SiC surface. The contact resistance of as-implanted and annealed samples using the sacrificial SiC wafer, were measured by the TLM method. Although contact resistance was found to decrease with increasing annealing temperature, sheet resistance increased, and contact resistance values were higher than expected, indicating that the heavy loss of Ga atoms contributed to the increased levels of contact resistance.

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