scholarly journals Polishing of Silicon Nitride Ceramic Balls by Clustered Magnetorheological Finish

Micromachines ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 304
Author(s):  
Xiao-lan Xiao ◽  
Guang-xian Li ◽  
Hai-juan Mei ◽  
Qiu-sheng Yan ◽  
Hua-tay Lin ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Analytical Model ◽  
Surface Finish ◽  
Experimental Results ◽  
Machined Surface ◽  
Silicon Nitride Ceramic ◽  
Ceramic Ball ◽  
Contact Points ◽  
Micro Morphology ◽  
Improve Surface Finish

In this study, a novel finishing method, entitled clustered magnetorheological finish (CMRF), was proposed to improve surface finish of the silicon nitride ( Si 3 N 4 ) balls with ultra fine precision. The effects of different polishing parameters including rotation speeds, eccentricities and the machining gaps on surface finish of Si 3 N 4 balls were investigated by analyzing the roughness, sphericity and the micro morphology of the machined surface. The experimental results showed that the polishing parameters significantly influenced the surface finish. The best surface finish was obtained by using the polishing parameters: the machining gap of 0.8 mm, the eccentricity of 10 mm and the rotation ratio of 3/4. To further investigate the influence of the polishing parameters on the surface finish, an analytical model was also developed to analyze the kinematics of the ceramic ball during CMRF process. The resulting surface finish, as a function of different polishing parameters employed, was evaluated by analyzing the visualized finishing trace and the distribution of the contact points. The simulative results showed that the distribution and trace of the contact points changed with different polishing parameters, which was in accordance with the results of experiments.

Self-Lubricated Modification for Silicon Nitride Ceramic Ball Surface

2010 ◽  
Author(s):  
Le Gu ◽  
Guangze Tang ◽  
Chuanwei Zhang ◽  
Cuini Jing ◽  
Liqin Wang
Keyword(s):  
Silicon Nitride ◽  
Solid Lubricants ◽  
Test Results ◽  
Silicon Nitride Ceramic ◽  
Ceramic Ball ◽  
Dlc Film ◽  
Dlc Coating ◽  
Ceramic Surfaces ◽  
Mos2 Film ◽  
Ball Surface

Some thin films were prepared as solid lubricants on the surfaces of silicon nitride ceramic disk and ball. DLC film about 500–800 nm thickness was deposited on the ceramic surfaces using ion implantation and deposition technology. The surface roundness measure results, as well as 80 to 90 nm, showed that DLC film was shaped uniformly on the ceramic ball surfaces. The ball-on-disk tests showed DLC coating on silicon nitride surfaces could lead the friction coefficient to about 0.1 and endure about 7h at 1.5GPa and 30 mm/s. Ball milling technology was employed to prepare MoS2 film on the ceramic ball surfaces. The film thickness and tribological test results showed that the thin MoS2 film on the ball surfaces, which hardly changed the surface roughness, also improved their wear behaviors.

The Friction and Wear of Silicon Nitride Ceramic with BSA Lubricant

2015 ◽  
Vol 642 ◽  
pp. 125-129
Author(s):  
Jing Ling Zhou ◽  
Chun Shu Zhai ◽  
Su Yun Yang ◽  
Shu Qian Wu ◽  
Guo Qing Wu ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Silicon Nitride ◽  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Bovine Serum ◽  
Friction And Wear ◽  
Physiological Saline ◽  
Deionized Water ◽  
Silicon Nitride Ceramic ◽  
Ceramic Ball

To research the friction and wear of silicon nitride ceramic with bovine serum albumin lubricant, the tribological properties of silicon nitride ceramic against stainless steel were investigated on CETR UMT-2 under lubrication of bovine serum albumin, deionized water, physiological saline and physiological saline mixed with bovine serum albumin. The worn surfaces of silicon nitride ceramic ball and stainless steel pin were examined with a digital microscope (VHX-2000). The friction coefficients of steady state are 0.26, 0.35, 0.69 and 0.8 under bovine serum albumin, physiological saline mixed with bovine serum albumin, physiological saline and deionized water. The lowest friction coefficient of steady state is 0.26 which is under lubrication of bovine serum albumin. The highest friction coefficient is 0.8 under the lubrication of deionized water. The measured worn areas of silicon nitride ceramic balls are 1282.3μm2, 1898.6μm2, 2753.9μm2 and 3645.7μm2 under bovine serum albumin, physiological saline mixed with bovine serum albumin, physiological saline and deionized water. The smallest worn area of silicon nitride ceramic ball is 1282.3μm2 which is measured under the lubrication of bovine serum albumin. The highest worn area of silicon nitride ceramic ball is 3645.7μm2 which was measured under the lubrication of deionized water. The same wear mechanism of silicon nitride ceramic ball had been found under the lubrication of bovine serum albumin, deionized water, physiological saline and physiological saline mixed with bovine serum albumin. The depth of scratches of worn surface of silicon nitride ceramic ball lubricated with BSA is 3μm which are the shallowest.

Development and Testing of High Temperature Silicon Nitride Microturbine Rotors

2008 ◽  
Author(s):  
Vimal Pujari ◽  
Ara Vartabedian ◽  
Gregg Wayman
Keyword(s):  
High Temperature ◽  
Silicon Nitride ◽  
Gas Turbine ◽  
Surface Finish ◽  
Systems Approach ◽  
Cutting Tools ◽  
High Yield ◽  
Machining Parameters ◽  
Dimensional Control ◽  
Machined Surface

Development and testing of gas turbine quality high temperature silicon nitride (NT154) components will be described. An advanced CNC green (using pressed powder blanks prior to densification) machining based complex shape forming methodology has been developed and successfully deployed to fabricate gas turbine quality rotor, vane ring and shroud components to net shape with high yield and required dimensional tolerances. Utilizing a systems approach involving green blank properties, type of cutting tools and machining parameters, the process has been optimized to achieve required as machined surface finish, dimensional control and part integrity. Integral bladed micro turbine rotors (IBR) and vane rings have been fabricated with dimensional control within 100 microns, surface finish within 1–2 microns. IBRs so formed have been successfully spin tested at room temperature at 40% above designed speed approaching maximum stress in the vicinity of 400 MPa.

scholarly journals Si3N4 Ceramic Ball Surface Defects’ Detection Based on SWT and Nonlinear Enhancement

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Dongling Yu ◽  
Huiling Zhang ◽  
Xiaohui Zhang ◽  
Dahai Liao ◽  
Nanxing Wu
Keyword(s):  
Silicon Nitride ◽  
Defect Detection ◽  
Surface Defects ◽  
Inspection System ◽  
Detection Accuracy ◽  
Threshold Method ◽  
Silicon Nitride Ceramic ◽  
Small Surface ◽  
Ceramic Ball ◽  
Ball Surface

In order to improve the detection accuracy and efficiency of silicon nitride ceramic ball surface defects, a defect detection algorithm based on SWT and nonlinear enhancement is proposed. In view of the small surface defect area and low contrast of the silicon nitride ceramic ball, a machine vision-based nondestructive inspection system for surface images is constructed. Sobel operation is used to eliminate the nonuniform background, and the silicon nitride ceramic ball surface image is decomposed by SWT. And frequency-domain index low-pass filtering is used to modify the decomposition coefficients, and an adaptive nonlinear model is proposed to enhance defects; finally, the image is reconstructed and segmented by the stationary wavelet inverse transform and the dynamic threshold method, respectively. The enhanced algorithm can effectively identify surface defects and is superior to traditional defect detection algorithms.

Modeling and Predicting Roughness of the Abrasive Jet Finishing with Grinding Wheel as Restraint

2010 ◽  
Vol 44-47 ◽  
pp. 975-979
Author(s):  
Ya Li Hou ◽  
Chang He Li ◽  
Yu Cheng Ding
Keyword(s):  
High Efficiency ◽  
High Surface ◽  
Experimental Results ◽  
Surface Shape ◽  
Grinding Wheel ◽  
Geometrical Parameters ◽  
Machined Surface ◽  
Carrier Fluid ◽  
Fluid Concentration ◽  
Micro Morphology

Based on the modeling and experiments concerning the surface roughness in abrasive jet finishing with grinding wheel as restraint, the effect of abrasive size, abrasive fluid concentration, machining cycles, wheel velocity and carrier fluid on machined surface quality was investigated. Surface grinder M7120 was employed in a jet machining experiment conducted with W18Cr4V and 40Cr materials, profilometer TALYSURF was used to measure the micro geometrical parameters after machining, and SEM was used to observe surface micro-morphology. Experimental results show that with W7 Al2O3 powder at the mass fraction of 10% and antirust lubricating liquid being adopted in jet machining for 20 to 30 cycles, not only high surface shape precision can be kept or obtained, but also defect-free machined surface with the roughness of Ra0.15～1.6µm can be obtained with high efficiency. Experimental observation and experimental results proved that the experimental results agree well with a mechanism-based machining model.

Analysis on the Factors of Surface Morphologies on Si3N4 Ceramic Internal Grinding

2017 ◽  
Vol 31 ◽  
pp. 44-52
Author(s):  
Jian Sun ◽  
Peng Zhou ◽  
Yu Hou Wu ◽  
Ke Zhang ◽  
Li Xiu Zhang
Keyword(s):  
Silicon Nitride ◽  
Grinding Wheel ◽  
Axial Vibration ◽  
Machined Surface ◽  
Silicon Nitride Ceramic ◽  
Linear Speed ◽  
Internal Grinding ◽  
Grinding Parameters ◽  
Feeding Speed ◽  
Surface Morphologies

Different grinding parameters of silicon nitride ceramic are researched at the process of internal grinding. The influences on the roughness of surface by the linear speed of grinding wheel (vs), radial feeding speed (f) and axial vibration speed (fa) are studied in the uniformity testing. The experimental equation of silicon nitride ceramic internal grinding is optimized. The machined surface morphologies of the ceramic specimen are measured by roughness instrument of Taylor-Hobson Surtroni-25 and scanning electron microscope of S-4800. The results show that with the increasing of the linear speed of grinding wheel the roughness of surface get reduced, and with the increasing of radial feeding speed the roughness of surface get raised. It is also inversely proportional to the axial vibration speed. The linear speed of grinding wheel has the biggest impact on the roughness of surface of the silicon nitride ceramic internal grinding among the three grinding parameters. With the increasing of linear speed of grinding wheel, the value of roughness of surface declines from 0.4095μm to 0.1726μm. The influences on the roughness of surface of the silicon nitride ceramic internal grinding by different factors are found out in the research, and its removal mechanisms are cleared up under different linear speeds of grinding wheel.

ALCOA 2024

Alloy Digest ◽  
1998 ◽  
Vol 47 (3) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Physical Properties ◽  
Surface Treatment ◽  
Tensile Properties ◽  
Surface Finish ◽  
High Strength ◽  
Machined Surface ◽  
2024 Alloy ◽  
Structural Applications ◽  
Strength Material

Abstract Alcoa 2024 alloy has good machinability and machined surface finish capability, and is a high-strength material of adequate workability. It has largely superseded alloy 2017 (see Alloy Digest Al-58, August 1974) for structural applications. The alloy has comparable strength to some mild steels. This datasheet provides information on composition, physical properties, and tensile properties. It also includes information on corrosion resistance as well as machining and surface treatment. Filing Code: AL-346. Producer or source: ALCOA Wire, Rod & Bar Division.

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