Abrasive Composites Research Articles

Kraft lignin/cubic boron nitride hybrid materials as functional components for abrasive tools

In this study, the kraft lignin/cubic boron nitride hybrid materials have been obtained and characterized for the first time. The effectiveness of the combination of lignin and boron nitride was evaluated on the basis of Fourier transform infrared spectroscopy. Furthermore, it was confirmed that the addition of cubic boron nitride (cBN) improved the thermal stability of the inorganic-organic material. Upswing in thermal properties allowed to apply the prepared materials in preparation of model abrasive composites. Beneficial influence of the lignin/cBN filler was also proven by a noticeable decrease in the amount of harmful phenol released from the compositions during headspace gas chromatography analysis. Mechanical properties of the lignin/boron nitride hybrids and resin systems were investigated by the three-point flexural test. The obtained results show that the used additives can be promising materials for abrasive tools combining the good properties of lignin as a plasticizer and of cubic boron nitride as a filler which improves the thermal and mechanical properties of finished products and, at the same time, limits the negative impact on human health and environment.

Mechanosynthesis of composites in chemically non-reacting and exothermically reacting systems for magnetic abrasive media

Magnetic abrasive machining is one of the advanced finishing processes that produce a high level of surface quality of any type. The productivity of the finishing process and the quality of the treated surfaces are determined by magnetic and abrasive properties of the working media. To synthesize effective magneto abrasive composites with the size range of 1–100 μm the intensive mechanical treatment of powdered mixtures of chemically inert (Fe:SiC, Fe:B4C and Fe:diamond) and exothermically reacting (Fe2O3:Fe:Me, Me = Al, Zr) systems in high-energy planetary ball mills is performed. It is shown that the formation of composites is the result of intensive processes of grinding and deformation (mechanical alloying) as well as of the mechanically intensified redox reactions (mechanochemical synthesis) leading to the formation of abrasive particles (MexOy) in iron matrix. X-ray diffraction, scanning electron microscopy, Mossbauer spectroscopy and investigations of mechanical properties accompanied by the measurements of the abrasive activity in the finishing process of the surface polishing are used for the characterization of the as-prepared composites. The main parameters and mechanisms of the formation of the optimal structure of composites are revealed. It is demonstrated that the smallest roughness of the machined surface (Ra ~ 1 nm) is achieved in the case of using the mechanically alloyed Fe/diamond composite and the mechanosynthesized Fe/ZrO2 composite.

Contact Deformation Behavior of an Elastic Silicone/SiC Abrasive in Grinding and Polishing

An elastic abrasive of the new type having the advantage of effectively controlled contact pressure and uniform deformation was developed. It provides complete lamination of the surface, effective treatment of the curved mold cavity, as well as improves the processing efficiency. It permits of fine cavity surface finishing. These soft elastic abrasive composites are based on silicone as the matrix material and modified SiC microparticles as the reinforcing element. Mechanics and contact deformation behavior of the abrasives were studied by examining sizes of reinforcing particles and their content (53.5, 59.3, and 65.4%). Mechanical compression behavior of the composite is characterized by the concave power function index. Contact deformation analysis shows that the network connectivity produced by cross-linking of silicone and a curing agent propagates through the void spaces of the crystal lattice of abrasive particles on pressure application. Elastic extension and compression of composite net chains guarantee the complete lamination of the processed surface, and hard abrasive particles introduced into the net chain spacing complement the structure of the material.

Activation of Magnesium Lignosulfonate and Kraft Lignin: Influence on the Properties of Phenolic Resin-Based Composites for Potential Applications in Abrasive Materials.

Magnesium lignosulfonate and kraft lignin were activated by different oxidizing agents for use in phenolic resin composites used for the production of abrasive components. The physicochemical properties of the oxidized materials were analyzed by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), dynamic mechanical-thermal analysis (DMTA) and inverse gas chromatography (IGC). The homogeneity of the model abrasive composites containing the studied products was assessed based on observations obtained using a scanning electron microscope (SEM). FTIR and XPS analysis of the oxidized products indicated that the activation process leads mainly to the formation of carbonyl groups. The IGC technique was used to assess changes in the surface energy and the acid–base properties of the studied biopolymers. The changes in the acid–base properties suggest that more groups acting as electron donors appear on the oxidized surface of the materials. DMTA studies showed that the model composites with 5% magnesium lignosulfonate oxidized by H2O2 had the best thermomechanical properties. Based on the results it was possible to propose a hypothetical mechanism of the oxidation of the natural polymers. The use of such oxidized products may improve the thermomechanical properties of abrasive articles.

Change in Slurry/Glass Interfacial Resistance by Chemical Mechanical Polishing

ABSTRACTThe use of ceria abrasives in the chemical mechanical polishing (CMP) of glass allows us to prepare extremely smooth surfaces because it aides both the chemical and mechanical aspects of the polishing process. The mechanism of CMP has remained vague, but the redox of Ce4+/Ce3+ would play a major role for the formation of hydration layer by the chemical factors of CMP. This redox accompanies the process of the charge transfer at glass/slurry interface. Electron charge carrier would be important role in chemical polishing if the redox reaction occurs during polishing. We then prepared the polishing model that it is possible to estimate slurry resistivity and the interfacial area specific resistance (ASR). The effects of abrasive compositions and slurry solution on chemical factor of CMP were investigated to clarify CMP mechanism. The hydration layer forms as a result of the shear stress during polishing but is independent of polishing loads. The amount of hydration layer as well as removal rate was increasing with increasing lanthanum concentration dissolved in ceria lattice. Small amount addition of NH4NO3 increase electron charge carrier density in slurry and improves removal rate, but excess addition inhibited hydration reaction by steric hindrance.

Dependence of the Specific Energy of Fracture of Ceramic Abrasive Composites in the System Kernel – Binder – Pores on Their Structure Parameters

A theoretical and experimental investigation of the influence of the structural parameters of ceramic compositions in the system abrasive kernel – binder – pores on their specific fracture energy is presented. The experimental procedure is described. A graphical interpretation of the experimental results and their analysis in the form of mathematical models for calculating the fracture energy of compositions with different structure is presented.

Finish Honing with Borium Hones of Friction Parts Bores of Wear-Resistant Highly Alloyed Nickel-Based Composites for Printing Machines

Background. The study on technological process of the finish honing-process of the bores of wear-resistant composite material parts, synthesized on the base of utilized and regenerated wastes of production from nickel alloys ХН55ВМТКЮ, ХН50ВТФКЮ ЭП975 with СаF 2 hard lubricant additions has been researched. Objective. The purpose of the work is the experimental research of processes of the finishing thin surface honing-process treatment with elbor hones of the surfaces of bores of the friction parts of the printing machines and, influence of abrasive tools composition in the first place, cutting modes, the construction elements of honing head on the roughness, quality, precision of bearing surfaces made of new composite nickel-based materials, and also on characteristics of specific capacity, the elbor take and technological self-cost of the honing-process operation. Methods. Surface treatment of printing machines nickel-based wear-resistance composite parts with the finishing thin honing-process on the honing-machines with the elbor hones on the ceramic bonds and application of thin cutting modes. Results. It was demonstrated, that granulosity, material of grain instrument and properties of the elbor hones bond for honing-process operations of the nickel-based composite parts essentially influence on the parameters of surface roughness, precision of surfaces, specific productivity, the elbor take, and technological self-cost of the process. The best parameters of surface roughness, precision of surface, productivity, specific expenses of elbor satisfy honing hones made of ordinary strength elbor (LO) with granulosity 7–14 μm on the ceramic bond (T1–T2) and thin honing-procession modes. Advantages of surface treatment of elbor hones at honing-process operation of different printing machines parts are shown. Conclusions. It was demonstrated, that quality of friction surfaces made of new nickel-based composite materials, and also economic factors of technological process of treatment (productivity, elbor take, cost of technological operation), substantially depend on the structure of elbor hones (granulosity, bond) and cutting modes. The recommendations on the production were developed.

Ocena wytrzymałości mechanicznej kompozytów ściernych z mikrokrystalicznego tlenku glinu zbrojonych wiskerami z wykorzystaniem analizy statystycznej Weibulla

Ocena wytrzymałości mechanicznej kompozytów ściernych z mikrokrystalicznego tlenku glinu zbrojonych wiskerami z wykorzystaniem analizy statystycznej Weibulla

Physicochemical Characterization of Functional Lignin-Silica Hybrid Fillers for Potential Application in Abrasive Tools.

Functional lignin–SiO2 hybrid fillers were prepared for potential application in binders for phenolic resins, and their chemical structure was characterized. The properties of these fillers and of composites obtained from them with phenolic resin were compared with those of systems with lignin or silica alone. The chemical structure of the materials was investigated by Fourier transform infrared spectroscopy (FT-IR) and carbon-13 nuclear magnetic resonance spectroscopy (13C CP MAS NMR). The thermal stability of the new functional fillers was examined by thermogravimetric analysis–mass spectrometry (TG-MS). Thermo-mechanical properties of the lignin–silica hybrids and resin systems were investigated by dynamic mechanical thermal analysis (DMTA). The DMTA results showed that abrasive composites with lignin–SiO2 fillers have better thermo-mechanical properties than systems with silica alone. Thus, fillers based on lignin might provide new, promising properties for the abrasive industry, combining the good properties of lignin as a plasticizer and of silica as a filler improving mechanical properties.

ABRASIVOS: UMA ANÁLISE DE DENTIFRÍCIOS COMERCIALIZADOS EM SALVADOR

Most toothpastes sold in Brazil contains abrasive composition with the function of preventing the formation of spots or pigmented film and burnish the tooth surface, however, the indiscriminate use of abrasives has generated discussion regarding the effects of this component. Objective: To evaluate dentifrices sold in the city of Salvador as to its commercial presentation, regarding the inormation contained in the packages related to abrasives, in order to verify if guidelines are offered to the public to assist them in choosing those products and to the professionals when it comes to the guiding elements of the prescription. Methodology: We have analyzed 45 packages of toothpaste, randomly purchased from supermarkets in Salvador, for two years. We have observed the following: component that guides the classification of toothpaste, type and concentration of abrasive and instructions with respect to the degree of abrasiveness. Results: All trademarks contained abrasive analyzed singly or in combination; eight types of abrasives have been found: Calcium Carbonate (27%), Silica (26%), Sodium Bicarbonate, Silicon Dioxide, Titanium Dioxide, trisodium phosphate, aluminum oxide and sodium silicate. Manufacturers have associated to the dentifrices naturals extracts with the purpose to prevent the dental color change without tooth and gengival aggression caused by abrasives associations. Conclusion: Lack of guidance on packaging about the level of abrasiveness of toothpaste that can guide patients and professionals to its rational use.

Engineering of polymers with a free volume in abrasive tool composites

The effect has been studied of a synthetic diamond powder as a filler on mechanical properties of polyhydroxophenylene containing copper as clusters incorporated into a polymeric mesh. The interrelation between the dispersion and filler concentration and a free volume, characteristic inherent in polymers, has been shown. It has been proved that the retention of diamond grains in a composite depends on the migration dynamics of the free volume elements.

Influence of different fillers on phenolic resin abrasive composites. Comparison of inverse gas chromatographic and dynamic mechanical–thermal analysis characteristics

The resin resol with selected zeolites fillers and abrasive grain (fused alumina) in a form of cuboid were studied as model material of investigated composites. Inverse gas chromatography (IGC) was used to determine the degree of hardening of studied resol and resol in the filler–resol composites. Dynamic mechanical thermal analysis (DMTA) was used for assessment of the influence of different inorganic fillers on the thermo-mechanical properties of phenolic resin, applied as a binder in manufacturing of abrasive articles. The application of IGC method supported by DMTA analyses makes possible to assess filler/resin interactions and hardening of resin matrix. These results can be applied in industry of abrasive articles. Moreover, presented measurements are cost-effective – there is no need to produce trial product. It was evidenced that fillers reveal significant impact on the thermo-mechanical behaviour of model semi-product used for production of abrasive articles.

Mechanichal Properties of DGEBA/TEPA Modified Epoxy Resin

The correlation between the structural network of a diglycidyl ether of the bisphenol-A (DGEBA) epoxy resin, modified by two distinct aliphatic amines (tetraethylenepentamine TEPA and jeffamine D230), and its mechanical properties, was investigated as possible matrix for abrasive composites applications. Both flexural tests, to determine the yield stress and the elastic modulus, as well as impact tests to determine the notch toughness, were performed. The DGEBA/D230 presented the highest stiffness and toughness but lowest yield stress. This epoxy network also displayed a greater plastic deformation during fracture.

Highly porous cubic boron nitride wheels for dry grinding

The paper addresses the influence of composition of highly porous cBN grinding wheels on the efficiency of grinding hardened steel with oil mist cooling and without cooling. Experimental investigations and statistical analysis of test data have demonstrated that the power intensity of the material removal process, workpiece heating, and ground surface roughness depend on the amount of cBN, pore-forming fillers, and vitrified bond in the abrasive mix composition.

Tools for precision diamond machining of spherical heads of endoprostheses from pure titanium

Abrasive composites based on modified epoxy resins and synthetic diamonds, which are three-level adaptive systems that make it possible to machine technically pure titanium without seizure, have been developed. The tools containing these composites have allowed us to elaborate an efficient technology of manufacturing heads of hip joints from technically pure titanium.

A research of the working surfaces of abrasive composites

In this paper, the method for the calculation of disperse fillers concentration on effective surface composite (active grains) is developed. The method is proven by research of composite materials on PTFE-bond containing diamond powders. The stability of active diamond grains in PTFE is defined by composite material density, uniformity of a powder and the relief characteristics of abrasive grains. In a tool on the polymeric bond without the adhesive interaction with filler it is preferable to use natural diamonds under condition of their qualitative classification. The developed method can be used for the estimation and prediction of the quality of tool composites containing the disperse fillers of micro-, submicro- or nanosizes with any form, a statistically regular distribution and casual spatial orientation.

Study of the Structural Organisation of Abrasive Composites Based on Ultrahigh-molecular-weight Polyethylene and Natural Diamond Powders

A study was made of the structural features of composite diamond-containing materials (CDMs) of abrasive designation, based on ultrahigh-molecular-weight polyethylene (UHMWPE) and natural diamond powders (NDPs), and their effect on the physicomechanical properties of the composite and the service characteristics of the tool. It was established that the composition of the composite is directly responsible for the parameters of the structure formed. It was shown that an increase in the degree of crystallinity and a reduction in the size of the supermolecular formations of the polymer binder lead to an increase in the physicomechanical and service characteristics of the material.

Diamond-Bronze Coatings for Grinding Applications

Grinding applications for the machining of stone and concrete require composite tools where large diamonds are perfectly embedded into a metallic matrix. With the detonation flame spraying process, it is possible to manufacture these super abrasive composites. Excellent embedment of the voluminous super abrasive particles into the matrix coating material can be realized to produce high quality composite layers for grinding applications of stone and concrete. In this paper, different diamond gradings as well as different volume contents of diamond in matrix are compared. Especially, the influence of particle size on its implantation efficiency is investigated and the influence of process and substrate temperature is analyzed. The thermal sprayed grinding tools are evaluated with respect to their microstructure as well as their grinding abilities. Compared to sintered diamond-bronze samples, the results of an adaptively designed grinding test for the machining of concrete are presented and analyzed.

Effect of Load on the Abrasive Wear of Silica-Filled Epoxy Resin Composites

In the present study, the influences of load on the abrasive wear properties of silica-filled epoxy resin composites were investigated at ambient temperature. The friction coefficient, wear rate and specific wear rate against SiC abrasive paper were determined experimentally. The sliding wear tests of the materials demonstrated that the friction coefficient and the wear rate of silica filled epoxy composites were lower than those of the pure epoxy. The cumulative wear volume tended to increase nonlinearly with increase of sliding distance and depended on diameter of the silica particle for all these composites. The friction coefficient and wear rate were raised substantially with an increase in applied load.

Procedure for Choosing Abrasive Composites for Grinding Materials that are Hard to Machine

A procedure is developed for choosing a composite abrasive for grinding alloys that are hard to machine based on considering the interaction of tool materials and the article being machined. The efficiency of the procedure is demonstrated using the composite created for machining titanium alloys.