Silicon Carbide Abrasives Research Articles

Friction and Wear Mechanisms of 316L Stainless Steel in Dry Sliding Contact: Effect of Abrasive Particle Size

The present work investigates the dry sliding friction and wear behavior of 316L austenitic stainless steel. Wear tests are performed on a pin-on-plane configuration against abrasive silicon carbide grains ranging from very large (200 μm) to small (15 μm) particles. The experiments are conducted at room temperature under different normal loads of 25–75 N. The wear damage mechanisms and wear debris are analysed using scanning electron microscope (SEM) observations. It is shown that for small abrasive particles, the friction coefficients increase with increasing normal load. However, for large abrasive particles, a reverse trend is observed. This difference is partly explained by a change in wear mechanisms.Finally, surface roughness measurment of the worn surfaces are performed after wear tests. The relationship between the 3D fractal dimension and wear rate is investigated based on fractal theory. The 3D fractal analysis of the worn surfaces showed that higher values of fractal dimensions indicate a larger real contact area and therefore a better wear resistance of the 316L stainless steel.

Evaluation of the Reuse of Waste from the Polish Porcelain in the Development of Ceramic Products with Better Thermal Comfort

The ceramic industry, and others industries of manufacturing and transformation of materials produce, in greater or lesser degree, a quantity of waste that are not reused or doesn’t have a destination ecologically correct. Finding a correct destination for this kind of materials comes being a big tool for society nowadays. In this context, this work proposes the use of waste-based abrasive silicon carbide to promote growth in ceramic bodies to obtain ceramics for better thermal comfort. The porcelain polishing’s residue was added to ceramic mass at different percentages of mass. These samples were sintered the 1.200oC. The results showed the increase in weight of the residue in the samples causes a decrease in the values of apparent and absolute density, and increasing the amount of pores in the material obtained. These pores are responsible for increased water absorption. Employing the program Quantikov was possible to determine the average pore size the sample; the samples identified as 1, 2 and 3 the increase in the content of waste to increase the average pore diameter opened. From the sample 3 to 7, the average pore diameter floats in an equilibrium value, an increasing the added amount of waste will increase porosity, but not its diameter. The sample 8 showed a low level of porosity. The results show the potential for reuse of the waste generated in the polishing of porcelain in the development of ceramics with better thermal comfort, reducing the impact caused by improper disposal and simultaneously reducing production costs.

Prediction of Optimal Process Parameters for Abrasive Assisted Drilling of SS304

This paper presents the optimization of cutting parameters for improving surface finish of stainless steel SS304 in the abrasive assisted drilling. In the present work, drilling of SS304 with supply of abrasive slurry consisting of silicon carbide abrasives of 1250 mesh size has been studied. The slurry concentration has been varied from 20-30% by weight. Abrasives slurry performs the dual function of cutting fluid as well as coolant. Response surface methodology (RSM) has been adopted for planning of experiments. Analysis of variance has been carried out to find out the significance and percentage contribution of process parameters and the interaction among various factors has been observed. The drilling parameters including spindle speed, feed rate, and slurry concentration are optimized using multiple performance characteristics for surface roughness. Although, feed rate and spindle speed are the most significant factors which affect the surface roughness but an overall improvement of approximately 11% in the surface roughness has been witnessed with the aid of abrasive slurry. These research findings provide useful economic machining solution in terms of optimized drilling conditions for drilling stainless steel SS304.

Measurement and model on thermal properties of sintered diamond composites

A prelude to the thermal management of grinding processes is measurement of the thermal properties of working materials. Indeed, tool materials must be chosen not only for their mechanical properties (abrasion performance, lifetime…) but also for thermal concerns (thermal conductivity) for efficient cooling that avoids excessive temperatures in the tool and workpiece. Sintered diamond is currently used for grinding tools since it yields higher performances and longer lifetimes than conventional materials (mineral or silicon carbide abrasives), but its thermal properties are not yet well known. Here the thermal conductivity, heat capacity and density of sintered diamond are measured as functions of the diamond content in composites and for two types of metallic binders: hard tungsten-based and soft cobalt-based binders. The measurement technique for thermal conductivity is derived from the flash method. After pulse heating, the temperature of the rear of the sample is measured with a noncontact method (infrared camera). A parameter estimation method associated with a three-layer nonstationary thermal model is used to obtain sample thermal conductivity, heat transfer coefficient and absorbed energy. With the hard metallic binder, the thermal conductivity of sintered diamond increased by up to 64% for a diamond content increasing from 0 to 25%. The increase is much less for the soft binder: 35% for diamond volumes up to 25%. In addition, experimental data were found that were far below the value predicted by conventional analytical models for effective thermal conductivity. A possible explanation is poor heat transfer at the diamond-binder interface. Indeed, better agreement between measurements and model was found by taking into account a thermal contact resistance between matrix and diamond particles equal to 0.75 and 1.25×10−6m2KW−1 for respectively the cobalt- and tungsten-based composites.

Abrasive jet polishing of micro-channels using compound SiC abrasives with compound additives

This study examined the performance of abrasive jet polishing (AJP) on SKD61 mold surfaces using wax-coated silicon carbide (SiC) abrasives fabricated by gas atomization, and the comparison of surface quality was achieved by revealing significant surface roughness which was reduced with wax-coated abrasives. The wax coating of SiC abrasives smoothens the sharp surfaces of abrasive powders and provides a cushioning buffer. These two features contribute and improve the direct impact of heavy peening, thus preventing surface hardening, superficial embedment, or deep scratches. Furthermore, compound additives including water wax and water were added to the wax-coated #3000 SiC abrasives at a mix proportion of 500:1,000:1,500 (water wax/wax-coated SiC/water) for polishing mold surfaces of different forms. The experimental results show that the compound additives provide additional cushioning effect which facilitates the sliding and grinding of abrasives, resulting in fine polishing and good surface quality. The reflection properties of both linear and curved micro-channels were much enhanced by the AJP using wax-coated #3000 SiC abrasives with the compound additives.

PENETRATION ABILITY OF ABRASIVE WATERJETS IN CUTTING OF ALUMINUM-SILICON CARBIDE PARTICULATE METAL MATRIX COMPOSITES

This article presents a set of studies performed on aluminum-silicon carbide particulate metal matrix composites prepared by adding 5, 10, 15 and 20% of SiC in aluminum alloy and processed with abrasive water jets that are formed with garnet and silicon carbide abrasives of 80 mesh size. These studies are essentially meant to assess the penetration ability of abrasive water jets on different compositions of Al-SiC p MMCs produced by stir casting method. Abrasive waterjet cutting experiments were conducted on trapezoidal shaped specimens of different composites as well on the constituent materials i.e., 100% aluminum alloy and 100% SiC specimens by varying water pressure, jet traverse speed and abrasive mass flow rate, each at three different levels. The percentage contribution of individual and combined effects of process parameters on penetration ability was analyzed by means of analysis of variance. Contribution of waterjet pressure and traverse speed on jet penetration in these meaterials are found to be more than abrasive flow rate. Among the interaction effects, waterjet pressure and jet traverse speed combinations contribute more to jet penetration. The results presented in this study can be used to build statistical models that can predict the depth of penetration of jet in different MMCs. This study also highlights the need to choose suitable abrasive mass flow rates and jet traverse speeds for effective processing of MMCs with abrasive water jets.

Measuring the flowing properties of powders and grains

A granular material is a complex system which exhibits non-trivial transitions between the static, the quasi-static and the dynamical states. Indeed, an assembly of grains can behave like a solid or a fluid according to the applied stress. In between solid and fluid granular states, very slow dynamics are observed. When a complete macroscopic characterization of a powder is needed, all these granular states have to be precisely analyzed. In this paper, we show how three measurement techniques can be used to measure the physical properties of a powder. The measurements are based on classical tests modified to meet the recent fundamental researches on granular materials. The static properties of the powder are analyzed through the shape of a heap. The quasi-static behavior is studied with the analysis of the compaction dynamics. Finally, the dynamical regime is monitored through the flow in a rotating drum. In order to illustrate how these measurements can be used in practical cases, analyses are performed with three types of granular materials: silicon carbide abrasives, flours and rice. These selected materials allow to show the influence of the different parameters (grain size, grain size distribution, grain shape) on the macroscopic properties of the assembly. Moreover, these studies show the pertinence of the parameters obtained with the proposed techniques for the rheological characterization of powders and grains.

다이아몬드 코팅 와이어로 가공된 태양전지용 실리콘 웨이퍼의 표면 특성에 관한 연구

현재 결정질 태양전지에서 웨이퍼 가공은 대부분 슬러리 분사 방식의 다중 와이어를 이용한 방법이 사용되고 있다. 이와 같은 슬러리 분사 방식의 웨이퍼 가공은 가공속도가 낮아 생산성이 떨어지는 단점이 있을 뿐만 아니라 금속 재질의 와이어와 실리콘 블록의 직접적인 마찰에 의하여 웨이퍼 표면의 금속 불순물에 의한 오염이 발생되는 단점이 있다. 뿐만 아니라 와이어와 실리콘 블록간의 직접적인 마찰로 인하여 와이어가 빨리 마모되며, 이로 인하여 일회성의 와이어를 사용하게 되면서 제조원가는 상승하게 된다. 반면에 다이아몬드 입자가 코팅된 와이어를 이용하여 실리콘 웨이퍼를 가공하게 되면, 가공속도가 기존 슬러리 분사방식보다 빠르며, 공정진행에 따른 와이어의 마모율이 적어 와이어의 재사용에 의한 제조원가 절감이 가능하다. 따라서 이와 같은 다이아몬드 입자가 코팅된 와이어를 이용하여 가공하는 기술은 슬러리 분사방식에 비하여 더 효율적이라 할 수 있다. 본 연구에서는 슬러리 분사방식으로 가공된 웨이퍼와 다이아몬드 코팅된 와이어로 가공된 웨이퍼의 표면특성에 대하여 분석하고 셀 공정에 영향을 미치는 것에 대하여 설명하고자 한다. 또한, 다이아몬드 와이어로 가공된 웨이퍼를 활용하기 위한 셀 공정의 개선방향에 대하여 제안하고자 한다. Most of the silicon cutting methods using the multi-wire with the slurry injection have been used for wafers of the crystalline solar cell. But the productivity of slurry injection cutting type falls due to low cutting speeds. Also, the direct contact with the metal wire and silicon block increases the concentration of metallic impurities in the wafer's surface. In addition, the abrasive silicon carbide (SiC) generates pollutants. And production costs are rising because it does not re-use the worn wire. On the other hand, the productivity of the cutting method using the diamond coated wire is about 2 times faster than the slurry injection cutting type. Also, the continuous cutting using the used wire of low wear is possible. And this is a big advantage for reduced production costs. Therefore, the cutting method of the diamond coated wire is more efficient than the slurry injection cutting technique. In this study, each cutting type is analyzed using the surface characteristics of the solar wafer and will describe the effects of the manufacturing process of the solar cell. Finally, we will suggest improvement methods of the solar cell process for using the diamond cutting type wafer.

Characterization of Silicon Carbide Grit for Fickerts Used in Porcelain Tile Honing and Polishing Process

This paper presents results of morphological and dimensional characterization of silicon carbide (SiC) abrasives used in production of fickerts for the rotary plane honing and polishing process of porcelain tiles. For morphological characterization scanning electron microscopy (SEM) and optical reflection microscopy images were analyzed by software to determine the circularity factor of the particles. In order to analyze the particle size dispersion sieving and laser diffraction were used. Five samples within the same batch of abrasives and with different sizes were characterized. The results show a uniform dispersion with a small variation of the particles size. Regarding the form of particles, the angularity increases in the samples with smaller size. The employed procedure for the analysis of circularity factor is a method frequently used to characterize SiC particles.

Experimental Investigations on Ice Bonded Abrasive Polishing of Copper Materials

In this article, an attempt is made to prepare an ice-bonded abrasive polishing (IBAP) tool, in situ, for ultrafine finishing of flat, Electrolytic Copper (EC)-grade copper specimen. Two different methods such as direct and layer-by-layer methods of freezing slurry were tried for preparation of the IBAP tool. Tools prepared by both these methods were characterized to analyze the distribution of abrasives in ice matrix. Polishing experiments were conducted on copper specimen by varying the rotational speed of tool, concentration of silicon carbide abrasives in slurry, contact pressure between tool and work surface, each at two levels. By analyzing the polished surfaces with an optical profilometer and scanning electron microscope, the mechanisms of material removal and surface generation processes are understood.

Recovery of silicon powder from kerf loss slurry by centrifugation

A feasibility study on recovering silicon powder from slurry containing silicon carbide abrasives, silicon kerfs, and iron fragments generated by slicing silicon ingots in the wire-saw process was conducted. The glycol solution and iron fragments in the slurry were removed using acetone and nitric acid, respectively. Then, centrifugation was applied to separate the silicon kerfs and silicon carbide abrasives using a heavy-liquid with a density between that of silicon and silicon carbide. The effects of several operational variables on the purity and yield of silicon kerfs were systematically investigated, including solid volume fraction, heavy-liquid density, number of centrifugation steps, and centrifugation time. Additionally, the effects of agitation for dispersing particles in the heavy-liquid before centrifugation were also studied. The purity and yield of Si product at specified conditions are reported.

A novel nanofinishing process using magnetorheological abrasive polishing fluid

Magnetorheological Abrasive Flow Finishing (MRAFF) is developed for finishing complex internal geometries up to nanometer level using Magnetorheological polishing (MRP) fluid which comprises of MR-fluid with fine abrasive particles dispersed in it. Experiments were conducted on stainless steel and silicon nitride workpieces using silicon carbide, boron carbide and diamond abrasives. The best surface finish obtained on the stainless steel workpieces with the present set-up configuration is 30 nm. The effect of number of finishing cycles, extrusion pressure and magnetic flux density is studied on change in surface roughness (Ra) value. Capillary magnetorheometer is designed and fabricated for rheological characterisation of MR-polishing fluid. Bingham plastic, Herschel Bulkley and Casson's fluid model are used to fit the obtained data points.

S1105-2-1 マイクロブラストにおける脆性材料のき裂進展挙動の評価([S1105-2]トライボロジーの基礎と応用(2))

The present study describes crack extension of ceramics during micro shot blasting. Various sizes of green silicon carbide and white alumina abrasives were used for the impact media and were collided to the target silicon nitride surface with a direct gas injection type blasting system. The eroded surface was analyzed with a SEM and a surface profile meter. The specimen was ruptured by a flexural test to observe the crack extension below the eroded surface region. Results showed that the crack extension was different depending on the materials and sizes of the impact abrasives and that the trans granular fracture occurred below the wear scar at smaller wear loss..

Resin–dentine interfacial morphology following CPP–ACP treatment

Objectives To evaluate the quality of bonded resin–dentine interfaces produced by two self-etching primer adhesives after casein phosphopeptide–amorphous calcium phosphate (CPP–ACP) treatment, in comparison to untreated dentine. Methods Thirty-four adult molar teeth were sectioned to obtain dentine with tubule orientations parallel/oblique or perpendicular to the surface. The specimens were divided into ‘smear layer’ (1A, 1B) and ‘no smear layer’ groups, after treatment with 15% EDTA (2A, 2B). The specimens were then left either untreated (1A, 2A) or treated (1B, 2B) with CPP–ACP paste (Tooth Mousse, GC Corp.) for 60 min × 7 days. Each treatment group was divided into three subgroups and specimens etched/conditioned (no conditioning; 30–40% phosphoric acid (H 3PO 4); 20% polyacrylic acid) and bonded with either a 2-step self-etching primer adhesive (Clearfil SE Bond, Kuraray Medical) or an ‘all-in-one’ adhesive (G-Bond, GC Corp.) and a hybrid resin composite. After 24-h water storage, the bonded specimens were sectioned, polished up to 4000-grit abrasive silicon carbide paper and 0.25-μm diamond paste, prepared for FE-SEM using the acid–base technique, critical point-dried, gold-coated and examined. Bonded and fractured dentine interfaces were also prepared and examined. Results The 2-step adhesive produced a similar appearance of bonded resin–dentine interface irrespective of smear layer group, treatment or etching/conditioning. After polyacrylic acid conditioning, the ‘all-in-one’ adhesive exhibited more areas with bond failures. The bond failures were within the hybrid layer and more pronounced following CPP–ACP treatment. Conclusion The quality of the bonded resin–dentine interface produced after CPP–ACP treatment may depend on the adhesive system used.

331 長繊維強化複合材料のエロージョン損傷機構に及ぼす投射条件の影響(摩擦・摩耗材料)

The present study describes effect of impact media size on erosive wear mechanisms of woven continuous SiC fiber reinforced ceramic matrix composites (CMC). The CMC was processed by chemical vapor infiltration (CVI) and consisted from fibers having 10 μm of mean diameter. Various size of green silicon carbide (SiC) abrasives used for the impact media were collided to the target CMC surface with pressurized air. Results showed that erosive wear rate and crack pass were different depend on the media size. A relationship between the crack pass and the erosive wear rate analyzed with the present erosive wear model based on the lateral crack extension.

Effects of thermal cycling and surface roughness on the Weibull distribution of porcelain strength

The objective of this study was to test the hypothesis that thermal cycling weakens the flexural strength of porcelain. Specimens of Deguceram Gold and Vita Omega 900 were tested in four groups of 30 specimens each: in the original glazed condition versus being ground with 1000-grit, 600-grit, and 100-grit silicon carbide abrasives. Corresponding to these four types of surface treatments, four groups of 30 specimens per group received 5,000 times of thermal cycling. Flexural strength was measured using a four-point flexural test, and Weibull modulus was calculated. Within each type of surface treatment, the thermal cycling treatment did not result in any decrease in flexural strength although it caused the Weibull modulus to become smaller - except for the control and thermal-cycled groups of 600-grit surface treatment.

Growth and Characterization of Silicon Carbide by Sublimation

Bulk silicon carbide (SiC) single crystal was fabricated by attaching abrasive SiC powder directly to graphite electrode. The substrate temperature was important to SiC crystal growth. When the temperature of substrate varied from 2300K to 2600K, with substrate temperature increase, the size of finally obtained SiC single crystal increased. At 2600K, the maximum size of SiC crystal, 2cm in diameter, was obtained. The effect of temperature to SiC single crystal growth rate and the growth kinetics were discussed. The phase composition and surface morphology was studied by XRD and SEM respectively.

Evaluation of continuous grinding tests on some marble and limestone units with silicon carbide and diamond type abrasives

This paper deals with the results of continuous grinding tests carried out with two different grinding machines on some marble and limestone units with silicon carbide and diamond type abrasives. The results showed that the relationship between the surface roughness and the surface glossiness of stones with homogeneous structure are independent of abrasive types. However, this argument is not valid for stones giving orange peel effect and not going through entire ductile behaviour due to their softer mineral and other materials content. Appropriate series of abrasives and operational conditions should be chosen for obtaining desired surface quality. For this reason, the results of surface quality measurements should be used in conjunction with stone properties.

Wear of bulk ceramics in micro-scale abrasion—The role of abrasive shape and hardness and its relevance to testing of ceramic coatings

There is a wide body of literature wherein the micro-scale abrasion test has been employed to assess the behaviour of a range of vapour-deposited ceramic coatings. However, the fundamentals of the micro-scale abrasion process with ceramic materials in general (both in monolithic form and as coatings) are not well understood. In this work, the micro-scale abrasive wear behaviour of a range of brittle materials was examined as a function of abrasive particle type and applied load. The three types of abrasive particle slurries were alumina, silicon carbide and diamond, of similar size distributions and all suspended in water. It was shown that the relative wear rates of the materials depended strongly upon the abrasive type selected. When the abrasives were harder than the testpiece in question, the behaviour was dominated by the angularity and the particle size distribution of the abrasive. High angularity and wide size distributions, observed with alumina and silicon carbide abrasives, resulted in the applied load being carried by a small number of abrasive particles which resulted in lateral fracture and high rates of wear, whereas blocky abrasives (such as diamond) resulted in the load being carried by a larger number of particles and thus lateral fracture being restricted with correspondingly low rates of wear. However, when the abrasives were either softer or not significantly harder than the testpieces, the relative hardnesses dominated the operative wear mechanisms. In previous work, it has been shown that ball roughness in the micro-scale abrasion test promotes abrasive entrainment into the wear zone throughout the test. In this work, it has been shown that high testpiece roughness as developed in the wear scar (due to lateral fracture being the primary mechanism of material removal) hinders further abrasive particle entrainment, and that testpieces which wear with a smooth surface morphology (by plastic flow rather than by brittle fracture) exhibit enhanced particle entrainment under conditions (such as high applied load) where other materials are demonstrating limited entrainment.

Precision Abrasive Jet Finishing of Cemented Carbide

Recently a technique has been developed to mold aspheric glass lenses by using cemented carbide dies at elevated temperature. The dies are precisely ground by an ultraprecision grinding machine. However the obtained form accuracy is generally around 100nm and is not enough high. In this study, to investigate a possibility of corrective figuring of the dies, a series of experiments of abrasive jet machining of cemented carbide was conducted and fundamental machining characteristics were examined. The used abrasives were fine grains of silicon carbide and aluminum oxide. The silicon carbide abrasives could accomplish a sufficient material removal. Both the material removal rate and the surface roughness increase as the collision angle increases up to 90 degrees. Therefore, in order to obtain a smooth surface finish, it was necessary to take a smaller collision angle and to slow down the material removal rate.