A Method and Device for Automated Grinding of Small Ceramic Elements

The paper describes an automated method for grinding small ceramic elements using a hyperboloid wheel. The problem of automating the process of machining elements made of nonmagnetic materials with a small area and low height has been solved. Automation of the grinding process was possible thanks to automatic clamping of workpieces in the machining zone and sequential processing by a specified number of grinding wheels. The workpieces were passed through successive machining zones. The division of the allowance of individual grinding wheels was made taking into account the characteristics of the workpieces and the requirements for the results of the machining. Obtaining a long grinding zone and the effect of automatic clamping of the workpieces was possible due to the inclination of the grinding wheel axis in relation to the plane of movement of the workpieces. Innovative aggregate grinding wheels were used for grinding. The aggregates containing diamond abrasive grains, connected with a metal bond, were embedded in the porous structure of the resin bond. The aggregates ensured high efficiency of grinding, and their developed surface contributed to good holding in the resin binder. The durability of grinding wheels was 64 h, which enables the machining of 76,000 ceramic elements.

Design and Performance of Ultrathin Overlay Epoxy-Rubber Concrete

Epoxy-rubber concrete has a big potential to be used for pavement overlays, but there is currently no appropriate epoxy-rubber concrete design method and process. To explore the reasonable mix design process of epoxy-rubber concrete, the ultrathin overlay aggregate gradation and epoxy resin binder with high toughness and durability were selected to carry out the design process investigation of epoxy-rubber concrete. The performance of epoxy-rubber concrete was characterized by vibration compaction, repeated load CBR, porosity, Fort Kentucky, uniaxial compression, bending, rutting, antiskid performance, and noise-reduction performance test. Firstly, the optimum range of the rubber powder replacement rate was determined based on the porosity and deformation characteristics of the aggregate mixture. Then, the amount of epoxy resin binder was further determined based on the porosity and antistripping performance of the epoxy-rubber concrete. Finally, the mechanical properties, road performance, and functions of epoxy-rubber concrete were comprehensively considered to determine the optimum rubber power replacement rate obtaining the composition design of epoxy-rubber concrete. The results showed that adding rubber powder decreased the elastic modulus and plastic deformation of the mineral structure, enhancing the suitability of the mixture for flexible road pavements. However, when the replacement rate increased to a specific range, the rubber particles significantly interfered with the mineral material, worsening the stability of the structure. Therefore, it was preliminarily determined that the reasonable replacement rate of rubber powder was 30–50%. The ultrathin overlay epoxy-rubber concrete exhibited excellent antistripping performance, and its porosity increased with the epoxy resin dosage. The optimum epoxy content was 6.5% at 4.17% porosity. Within the preliminarily determined replacement rate range of rubber particles, as the replacement rate increased, the flexibility, high-temperature stability, antiskid performance, and shock and noise resistance of the mixture increased, but the compressive and flexural tensile strength values decreased. The integrated properties of the ultrathin overlay epoxy-rubber concrete indicated that the best replacement rate of rubber powder was 45%. In this paper, the replacement rate range of the rubber powder was initially determined based on the gradation composition of the mixture, which avoids blind determination of the replacement rate. And the composition of the concrete was obtained comprehensively by the performance and function of the epoxy-rubber concrete, which is reasonable and reliable. The epoxy-rubber concrete design method proposed in this paper can promote the application the epoxy-rubber concrete in pavement overlay engineering.

Proposal for a Novel Abrasive Machining Method for Preparing the Surface of Periarticular Tissue during Orthopedic Surgery on Hip Joints

Drilling, cutting, and milling are the most common methods used in orthopedic surgery. However, popular machining methods do not obtain the complex shape of the periarticular tissue surfaces, increasing operation time and patient recovery. This paper reports an attempt to research a novel design of a machining process for surgical procedures. A device using abrasion machining based on mechanical erosion was proposed. Machining uses an undefined geometry of the cutting grains to cut tissue in any direction during oscillatory tool movement. This new concept is based on a cylindrical abrasive device made of brown fused alumina and silicon carbide grains deposited with an epoxy resin binder on the surface of a polyamide shaft. The best results in terms of machining efficiency were obtained for grains of the BFA80 type. Cutting experiments with different values in terms of cutting speed, granulation of the abrasive grains, pressure forces, and machining scope showed that the proposed concept, by developing the shape of the device, allows for penetration of the tissue structure. The research shows the possibility of using the proposed method during periarticular tissue machining.

Study of the Effect of Tungsten Carbide Nanopowder Agglomerate Additives on the Strength Properties of Carbon Fiber-Reinforced Plastic

The paper presents the results of tests of carbon plastic samples consisting of carbon fabric Grafill TR30S-S (Italy) and epoxy resin binder EPR 320 modified by WC tungsten carbide nanopowders in the form of agglomerates. The positive effect of additives on the tensile strength and on the modulus of elasticity at transverse bending of the concentration of additives 1-3% is shown.

Kuznets curve with parabola-shaped ultra-wideband antenna with defected ground plane for communications

Purpose This paper aims to state the configuration of the proposed antenna which is competent to many networks such as LTE and X band applications. The experimental study encountered the significance of the proposed antenna. Design/methodology/approach A novel compact Kuznets curve with parabola-shaped quad-band notched antenna is demonstrated in this paper. The presented prototype is ascertained on a composite material composed of woven fiberglass cloth with an epoxy resin binder. The resulting ultra-wideband antenna ranges 3.1–3.54 GHz, 5.17–5.51 GHz, 5.74–6.43 GHz and 6.79–7.60 GHz. To avoid the frequency bands which cause UWB interference,the projected antenna has been incorporated with slotted patch. The proposed antenna design is attained in four steps. The simple circular patch antenna model with defected ground plane is subjected to stepwise progression by including parabola-shaped slot and U shaped slot on the patch to attain four notched bands. Findings This projected antenna possesses an optimal bond among simulated and measured outcomes,which is more suitable for the quad notched band applications. Substrate analysis is done by varying substrate material, and notch behavior is presented. The proposed method’s optimum performance in metrics such as return loss, voltage standing wave ratio and radiation pattern varies its frequency range from 2.56 to 7.6 GHz. Originality/value The antenna adaptation of the defected ground plane has achieved through the quad notched band with operating frequency ranges 2.56 to 7.6 GHz and with eliminated frequency ranges 3.55–5.16 GHz, 5.52–5.73 GHz, 6.44–6.78 GHz and 7.66–10.6 GHz.

Functionalization of alumina particles to improve the performance of eco-friendly brake-pads

Abrasives, such as oxides of alumina (Al), silica (Si), zirconia (Zr), chromium (Cr) etc., are added to raise the friction level and also to remove the glaze on the disc so that surface will be rejuvenated continuously during braking and will contribute to maintain the desired friction level. However, these inorganic particles have less adhesion with the resin/binder and hence are easily dug out during wearing process contributing to higher wear. If efforts are made to enhance the filler-matrix adhesion, not only the wear of friction material (FM) should reduce, the particles may stay for a longer time on the tribo-surface of the pads to contribute fully towards controlling the coefficient of friction (μ). In the present study, alumina particles were selected for siloxane treatment to improve the filler-matrix adhesion. Two types of eco-friendly (free from asbestos and Cu) brake-pads were developed using alumina as a theme ingredient (treated and untreated) keeping all the parent formulation identical. An additional type of brake-pads without alumina particles was also developed to observe the effect of abrasive particles on the tribo-performance. The performance properties (physical, mechanical, and tribological) of brake-pads were compared when evaluated in identical conditions. The tribo-testing was done on full-scale brake inertia dynamometer following the procedure in Japanese automobile standard (JASO C 406). It was observed that siloxane treatment affected both friction and wear of brake-pads in a beneficial way. Wear resistance got increased 35% for siloxane treated pads. Worn surfaces were analysed using scanning electron microscopy (SEM) and energy dispersive X-ray (EDAX) technique.

RESEARCH OF WAYS TO INCREASE CORROSION RESISTANCE IN REINFORCED CONCRETE CONSTRUCTIONS. PART 2

The article presents the results of the fi nal series of tests on the study of ways to increase the corrosion resistance of reinforced concrete structures with primary protection in the form of an addition of acetone-formaldehyde resin ACF-75 and with secondary protection with a two-component resin Binder EP 11 Tikso. An analysis of the change in the adhesion strength of secondary protection elements with a concrete surface after exposure to sulfuric and nitric acid, as well as the eff ect of the presence of a preliminary primer on a concrete surface on the intensity of adhesion change is presented. Conclusions are drawn about the possibility of using a two-component resin Binder EP 11 Tikso as a secondary protection against corrosion destruction of concrete in the process of reinforcing reinforced concrete structures operating in environments containing sulfuric and nitric acids.

ANALISA SIFAT MEKANIK PENGARUH VARIASI PERENDAMAN DAN PENEKANAN PADA KOMPOSIT BERBAHAN SERAT BUNDUNG

This study aims to determine the effect of mechanical properties of impact, bending and tensile of bundle fiber composites with 5% NaOH variation of immersion time 0.5 hours, 1 hour and 1.5 hours. Then the blending and casting process is carried out to form a composite material with 20% fiber and 80% resin binder with a catalyst content of 1% and pressurized with press variations of 5 kg, 10 kg and 15 kg. The results of the blending and casting process are made according to the testing standard and then testing the mechanical properties. Impact, bending and tensile strength test results showed that immersion of 0.5 hours with 15 Kg concentration produced the highest value, namely Impact strength 94.89 J / mm2, bending strength 17.77 N / mm2 and tensile strength 27 N / mm2. Whereas the fracture form of the composite is the binding and fiber breaking evenly at the same point and the fiber is not pulled from the metric.