Abrasive Characteristics Research Articles

Assessing the impact of trawling on benthic megafauna: comparative study of video surveys vs. scientific trawling

Abstract Most studies about benthic community use small-scale sampling methods focused on the infauna such as grabs or box-corers. The benthic data collected by scientific trawl surveys in all European waters, in the frame of the Common Fishery Policy Data Collection Multiannual Program, can be used to study the impact of large-scale fisheries such as trawling. However, the catchability of trawls is very dependent on the nature of the seabed as well as resulting ground-gear adaptations. Due to its non-destructive nature and its ability to focus on benthic macro-epifauna, towed video sampling appears to be a good alternative to monitor the impact of trawling on benthic communities. In the present work, we studied the influence of fishery induced seabed abrasion and video characteristics on nine indices, which can be used to monitor the effect of trawling on benthic communities, was studied. Among them, three indices specific to fishery effect detection based on biological traits appeared to be the best performing benthic indices with video data: modified-Trawling Disturbance Index, partial-Trawling Disturbance Index, and modified sensitivity index. The effectiveness of these indices to monitor the effect of trawling was evaluated and compared between trawl and video sampling. This work has highlighted that video sampling could be a good alternative, or at least a complementary method, to scientific trawling to monitor the effect of trawling on benthic communities in European waters.

Selection of optimal processing condition during abrasive wear of in-situ ZA-37/TiCp composites using MCDM technique

The present study attestation has been made towards microstructural characterization, and thereafter investigation on the optimum abrasive wear processing condition of newly developed insitu TiC reinforced ZA37 alloys. The MMC's have been processed by advanced vortex creating in-situ technique. Effects of significant influencing variables like abrasive grain size, percentage of reinforcement, applied load, and sliding velocity on abrasive wear characteristics via wear rates, coefficient of friction and interface temperature was investigated thoroughly. A newly developed, GRA based hybrid RSM approach has been implemented to investigate the optimum processing condition within the specified wear domain. The non-linear characteristics of response variables were demonstrated by developing a quadratic regression model which was the functions of independent process variables. ANOVA has been implemented to identify the percentage contribution of each process variables towards responses. The observation revealed that the abrasive grain size, percentage of reinforcement and applied load contributed significantly to the developed model and thereby on the wear characteristics. Improvements were noticed on the response characteristics attained by implementing both the GRSM and desirability approaches. Significant deviations were obtained on responses (15% on wear rates, 20% on COF and 4% on temperature) implementing two phases of optimal parametric combinations predicted by GRA based hybrid approach. Optical surface profile and corresponding micrograph represent the improved surface quality (Ra, 0.83 μm vs. Ra, 1.18 μm) and textures employing the GRSM based hybrid approach indicated settings of the process parameter.

Design and development of a novel sliding friction and wear tester with complex working conditions

Serious wear phenomena occur in mining machinery under complex working conditions, and the wear of machine parts is primarily caused by the synergistic effect of adhesive wear, abrasive wear, corrosive wear, etc. However, the existing friction and wear testing equipment cannot be used to carry out wear tests under complex working conditions. To simultaneously meet the test requirements of adhesive wear, abrasive wear, and corrosive wear, a novel sliding friction and wear tester that can simulate complex working conditions was developed in the present research. The tester is composed of a loading mechanism, a speed-regulating mechanism, a corrosion chamber, and a control and display system. Wear tests of the middle plate of a scraper conveyor, a key equipment of coal mining, were carried out to verify the consistency and effectiveness of the tester. The test results were consistent, and those under the same test conditions were similar with a maximum standard deviation of 2.4 mg. The wear condition of the middle plate specimens was close to the actual wear condition of the middle plate. Moreover, the surfaces of the middle plate specimens after grinding exhibited obvious adhesive, abrasive, and corrosive wear characteristics, and the wear degrees of the specimens under the same test conditions were similar. The quality loss of the middle plate specimens was found to increase with the increase of coal gangue percentage, and the main wear mechanism was the synergistic action of abrasive, adhesive, and corrosive wear.

Single-point scratch testing for understanding particle engagement in abrasion of multiphase materials

The current research explores the influence of multi-asperity abrasive particles engagement on multiphase materials. WC-Co (WC-15.6% Co) and NbC-cermet (NbC-12% Ni–10% Mo2C) hard materials were tested using a scale down single point scratch tester. Multi-asperity scratch patterns were produced by implying multiple scratches on hardmetal surface by parallel and repeated sliding. Superimposition of interactions has been implemented to study the damage evaluation of close-up parallel scratches. The abrasive particle characteristics such as size and apex angle were replicated by the diamond indenter and their influence with different applied loads [1–20 N] and sliding speeds [0.2–5 mm/s] were studied. NbC-cermet and WC-Co show a decrease in friction coefficient by 20–46% and 11–30% respectively, while the indenter tip radius changes from 200 μm to 25 μm under the same operating conditions. The wear micro-mechanism mainly changes from plastic deformation to fracture when the load and tip radius is increased. An extensive comparative study shows NbC-cermet prematurely experiences fracture dominated failure than its reference WC-Co. Moreover, tip size defect from indenter curvature geometry greatly affects the mean apex angle.

Holocene grinding stones at Madjedbebe reveal the processing of starchy plant taxa and animal tissue

The functional study of ground stone artefacts and the analysis of charred plant remains together demonstrate that plant foods played a significant role in the diets of Aboriginal Australians through all occupation phases at the Pleistocene-aged archaeological site of Madjedbebe. Here we report studies of three sandstone grinding stones from the Holocene levels of the site, one associated with a radiocarbon age of 690 cal. BP, and the others with an age of 8320 cal. BP. The functional analyses involved technological studies combined with brightfield microscopy, starch grain analysis, biochemical testing and gas chromatography-mass spectrometry (GC–MS). All three tools had usewear consistent with plant processing, with two having abrasive smoothing and polish characteristics typical of seed-grinding. Significant quantities of starch were recovered from each artefact and demonstrate the early Holocene processing of waterlily (Nymphaea violacea) and possibly kapok bush root (Cochlospermum fraseri), cheeky yam (Amorphopallus galbra) and long yam (Dioscorea transversa). In addition to starchy plant foods, one of the tools was used for processing animal tissue, as indicated by biochemical testing and GC–MS analysis, inferring a multi-functional use.

Numerical and experimental study on the ultrasonic-assisted soft abrasive flow polishing characteristics

To resolve the low-polishing efficiency problem caused by the turbulent layer separation in soft abrasive flow (SAF) processing, an ultrasonic-assisted SAF (UA-SAF) method is proposed based on the vibration effect. The coupled computational fluid dynamics (CFD)-discrete element method (DEM) modeling method (CFD-DEM) and the dynamic mesh are used to represent the UA-SAF flow and the periodic moving boundary caused by ultrasonic vibration, while the particle-wall erosion is calculated by the Archard model. Through tracking the abrasive particle motion in the simulation, the particle-wall collision states and the particle cutting effect are revealed, which mainly includes the particle plowing and the particle impact erosion. It has been found from the simulation that the fluid turbulent motion and the fluid dynamic pressure which are the power source for the particles to obtain the anisotropic cutting kinetic energy can be strengthened obviously by the ultrasonic vibrating, which results in the increase of the probability of particle impacting the target surface, and then the particle-wall wear rate and the wear area can be improved. A set of comparative experiments, including the rough and precision polishing procedures, are then conducted to evaluate the polishing performance by using the SAF and UA-SAF, respectively. The variations of the surface roughness and the workpiece mass are obtained, and the surface morphologies are observed. The experimental results prove that the ultrasonic vibration can effectively improve the abrasive flow polishing efficiency and precision without producing cavitation erosion.

Methodological Approaches to the Formation of the Soil Abrasive Characteristics and Wear of Tillage Machine

When performing various technological operations in crop production, the working bodies of tillage equipment in contact with the soil wear out under the influence of an abrasive environment. (Research purpose) The research purpose is in theoretical substantiation for a method for quantifying the wear capacity of soils with different abrasive characteristics. (Materials and methods) The article presents the evaluation of the abrasive ability of the soil by the wear of a steel rod vertically immersed in the soil and moving translationally. Authors used the standard rod of steel St0; geometric parameters of the worn rod are diameter d = 25-30 millimeters, height h = 250 millimeters; dynamic characteristics during the test are moving speed V = 3 kilometers per hour, distance of movement L = 100 meters. The worn rod sinks to a certain depth, moves in the soil at a constant speed. A device was used to determine the abrasive characteristics of the soil. (Results and discussion) The numerical characteristic of the wear capacity of the soil was determined as the physical value of the wear of the standard worn rod when moving in the soil as A=Q/L, grams per meter. The lower the value of this ratio, the less abrasive components are in the soil; based on the wear data of a standard rod, it is possible to obtain a characteristic of the wear capacity of various soils. (Conclusions) The proposed method allows us to determine the abrasive and wear characteristics of various types of soils. The results of the study make it possible to install working bodies on tillage machines in accordance with the type and wear capacity of the soil in which they will work, which will reduce the cost of their manufacture and increase the efficiency of the use of equipment.

Tribological Properties of Fly Ash Blended Polymer Composites

In this study, it was studied that the abrasion resistance and characteristics of polymer composites with fly ash (FA). The epoxy based polymer composites are produced with resin and FA as mineral additive. Mixtures of different ratio by replacing the FA were added to the resin from 0 to 30% by weight. Polymeric samples were cured in air conditioning and they were taken from the molds after 24 hours. Polymeric samples gain ultimate strength after 7 days. Therefore, abrasion tests were performed on 7 aged specimens. Abrasion characteristics of polymer composites were defined by pin-on-disc test for 500 m under a dry friction condition and room temperature. Three types of loading conditions were carried out as 5, 10, 15 and 30 N. The hardness and wear resistance values increased with the increase in the content of fly ash. Showing the relationship between wear rate and hardness, an equation with parameters dependent on load was provided. There was an increase in the friction coefficient with an increase in the surface roughness values. In addition, dynamic friction was as a function of the wear rate. The wear surfaces of the polymer composites were analyzed using scanning electron microscopy. It was observed that the wear rate of the polymer composites and pure epoxy samples ranged from 17.82 to 172.96 mm3/Nm.

Assessment of Durability and Service Life of Two-Layer Hardened Earth Cutters in Various Soil Conditions

Introduction. The earth cutter resource depends on the characteristics of the materials they are made from. In particular, the important parameters that directly affect the tillage tool parts efficiency and durability are the values and ratios of the coefficients of relative wear resistance of the two-layer parts materials, as a rule of the hardened deposited layer and the base material (steel). It is established that the characteristics of the relative wear resistance of the materials for earth cutter parts vary depending on the treated soil properties. The objectives of the study are to consider the influence of soil conditions on the values of the relative wear resistance coefficients of two-layer earth cutter part materials and to carry out a comparative assessment of their resource and use efficiency. Materials and Methods. The authors gave a generalized dependence of the wear proportionality to the existing specific pressures values. The characteristics of soil abrasion were given. The scientific substantiation of the changes in the characteristics of the materials wear resistance at various values of specific pressures was given. Results. The results of the operational resource tests and the studies of two-layer and monometallic earth cutters are presented. The influences of the values of the operating specific pressures on the coefficients of the relative wear resistance of the materials for the tillage machine parts are determined. Discussion and Conclusion. The authors have found out that the coefficients of relative wear resistance of materials are not constant, but vary depending on the current surface specific pressures. The correlation of the specific pressure values with the parameters of the tillage operation, in particular with the furrow slice hardness was established. It has been found that while increasing the cultivated soil hardness, the coefficients of various materials relative wear resistance get closer to each other. The difference varies from 1.80 to1.85 times.

빙-콘크리트 마찰 특성 평가를 위한 실험적 기초 연구

Ice induced abrasion is known as a critical problem in concrete gravity based offshore structures, which are mainly used in the arctic regions. Although many researches on ice abrasion have been conducted for the last several decades, there still are some difficulties in designing concrete gravity based offshore structures against abrasion problem because there is no standardized method yet due to the uncertain physics involved in. This paper presents an experimental study for the evaluation of concrete abrasion characteristics due to ice friction on concrete surface. For the test, a testing machine capable of abrasion and friction was designed and produced, and standardized procedure was proposed to produce ice specimen used for abrasion test. For the experiment, compressive strength of the ice specimen were explored through a static compression test. Then the friction test between ice specimen and concrete surface was performed and friction coefficients were derived using measured vertical and horizontal forces. Dependency of friction coefficients on some test parameters were studied and discussed as well.

Abrasion, sliding wear, corrosion, and cavitation erosion characteristics of a duplex coating formed on AZ31 Mg alloy by sequential application of cold spray and plasma electrolytic oxidation techniques

In order to improve the comprehensive surface properties (corrosion and wear resistance) of an AZ31 Magnesium (Mg) alloy, the Cold Spray (CS) and the Plasma Electrolytic Oxidation (PEO) techniques were utilized sequentially to fabricate a double-layered (duplex) coating. An alumina (Al2O3) reinforced aluminum CS layer was first deposited on the AZ31 Mg alloy substrate surface, and the PEO process was applied on the CS layer subsequently to obtain an Al-based PEO coating. The microstructure, mechanical properties, corrosion, abrasive wear, dry sliding wear, and cavitation erosion resistances were evaluated to quantify the surface condition before and after the aforementioned treatments. The results revealed that the Al-based PEO coating possessed more compact microstructure, higher micro-hardness (1100 HV0.025) and higher bond strength (27 MPa) than the Mg-based PEO coating (412 ± 61 HV0.025 and 20 MPa). The Al-based PEO coating also offered a superior protection to AZ31 Mg alloy against abrasion (0.010 mm3/N m, dry sliding wear (5.14 × 10−5 mm3/N m, corrosion (5.18 × 10-7 A/cm2), and cavitation (5 × 10-4 mm3/s) compared to the single-layered coatings (Mg-based PEO coating and CS coating).

Investigation of three-body abrasive wear characteristics of white ark shell powder

Abstract In this work, white ark shell powder (a natural sea waste) was investigated for its abrasive character using dry abrasion tester with two other commercially available materials i.e., American Foundrymen’s Society (AFS) quartz sand and cashew nut shell liquid (CNSL) friction powder. A total of 54 experiments were performed on dry abrasion tester using these powdered materials against a grey cast iron (GCI) specimen at two different wheel speeds of 100 r.p.m. and 200 r.p.m. with varying wheel revolutions from 250 to 750 under the loads of 38 N, 51 N and 64 N. The particle size was kept in the range of 50–70B.S.S. mesh. It was observed that the volume loss of GCI specimen increased with increase in load and wheel revolutions at both the wheel speeds. The increase in wheel speed from 100 r.p.m. to 200 r.p.m. also influenced the volume loss significantly. The wear volume loss at all the combinations of wheel revolutions and wheel speed for the tested abrasives in decreasing order was observed as: AFS quartz > CNSL powder > white ark shell powder. The lower volume loss of counter surface against white ark shell powder suggests its use in such applications where low wear rate is required.

Optimization of Rubber Compound Design Process Using Artificial Neural Network and Genetic Algorithm

In the rubber industry, the process of designing rubber compound is of great importance due to the impact on product specifications. The good performance of this process is a competitive advantage for manufacturers in this industry. The process of designing a rubber compound includes a set of activities related to selecting the best amount of raw materials to prepare a composition with the desired physical and mechanical properties. Currently, the most common method for designing a rubber compound is the experimental method based on trial and errors. This method is time consuming and expensive. In addition, the obtained combination is not necessarily the best combination. To improve the performance of the rubber compound we need to design the desired process, this research presented using a combination of artificial neural network and genetic algorithm, with an approach to reduce time and cost, while increasing accuracy. In this method, the behavior of the rubber compound was modeled with artificial neural network. Then, using Genetic Algorithm as a quick search technique.The optimal values of the four raw materials such as carbon, sulfur, oil and accelerator; in order to determine the specified value of the two characteristics .abrasion and rubber modulus at 300% elasticity at the lowest price. To evaluate the method, several samples of rubber compound designed with two method. The results showed that the artificial neural network model has the ability to predict the two characteristics of abrasion and modulus based on the four mentioned raw materials in the trained range with high accuracy. In addition, average results for genetic algorithm, is a price of 17% less and a design accuracy of 84.5% more than experimental method. The design speed with this method is 454 times higher than the experimental design speed. Based on the results, by designing the rubber compound with the integration of artificial intelligence and genetic algorithms has a better performance than the experimental method.

Hole quality in longitudinal–torsional coupled ultrasonic vibration assisted drilling of carbon fiber reinforced plastics

Carbon fiber reinforced plastic (CFRP) composites are extremely attractive in the manufacturing of structural and functional components in the aircraft manufacturing field due to their outstanding properties, such as good fatigue resistance, high specific stiffness/strength, and good shock absorption. However, because of their inherent anisotropy, low interlamination strength, and abrasive characteristics, CFRP composites are considered difficult-to-cut materials and are prone to generating serious hole defects, such as delamination, tearing, and burrs. The advanced longitudinal–torsional coupled ultrasonic vibration assisted drilling (LTC-UAD) method has a potential application for drilling CFRP composites. At present, LTC-UAD is mainly adopted for drilling metal materials and rarely for CFRP. Therefore, this study analyzes the kinematic characteristics and the influence of feed rate on the drilling performance of LTC-UAD. Experimental results indicate that LTC-UAD can reduce the thrust force by 39% compared to conventional drilling. Furthermore, LTC-UAD can decrease the delamination and burr factors and improve the surface quality of the hole wall. Thus, LTC-UAD is an applicable process method for drilling components made with CFRP composites.

Effect of Nanosilica and Crosslinking System on the Mechanical Properties and Swelling Resistance of EPDM/SBR Nanocomposites with and without TESPT

The ethylene-propylene-diene monomer/styrene-butadiene rubber (EPDM/SBR)-nanosilica (SiO2) nanocomposite was prepared. The 0–10 parts per hundred rubber (phr) of SiO2 with EPDM/SBR was mixed on a two-roll mill. The effect of nanosilica (0–10 phr), crosslinking system (sulphur, dicumyl peroxide and mixed) and silane coupling agent (bis(triethoxysilylpropyl)-tetrasulphide) on the curing characteristics, mechanical properties, rebound resilience, compression characteristics, abrasion, swelling property and morphological characteristics of the EPDM/SBR-SiO2 nanocomposites was investigated and studied. From the results, it was clear that the mechanical, wear and swelling properties steps-up with increase in the content of nanosilica particles in it. The sulphur cured rubber composite exhibits an overall improved properties as compared with other crosslinking agents such as peroxide and mixed systems. The addition of silane coupling agent (SCA) enhances the properties of the nanocomposites to a greater extent. From the analysis, it was clear that the effect of nanosilica concentration in the rubber composite with SCA was found to be superior compared to nanocomposites without it.

Clinical characteristics of treadmill abrasion in children

Objective: To analyze the clinical characteristics of treadmill abrasion in children. Methods: The medical records of 12 children with treadmill abrasion who were admitted to Tongren Hospital of Wuhan University & Wuhan Third Hospital (hereinafter referred to as the author's unit) from August 2017 to August 2019 were retrospectively analyzed. The data of gender, age, time of seeing a doctor after injury, injury environment and cause, abrasion site, abrasion area, abrasion depth, and wound treatment method and outcome of children were analyzed. Results: (1) The children included 5 males and 7 females, with the age of 2 to 6 years. Three children were treated on the same day after injury, and 9 children were treated 7 to 15 days after injury. (2) All the children were injured at home, and the abrasion was mainly caused by touching the running treadmill when their parents were using it. The contact area was mainly the gap between the rear track axle and the metal plate at the lower edge. (3) All the children had abrasion in the hands. The index finger, middle finger, and ring finger were the main involved fingers. The area of the abrasion was 2 cm×2 cm to 8 cm×5 cm, all of them were deep-partial thickness and above. (4) The children were mainly treated in outpatient department (9 children), and 10 children were conducted with conservative treatment. Eleven children had local scar formation, after anti-scar treatment and functional exercise, they recovered well without obvious dysfunction. Conclusions: Hands in those children are the most vulnerable part of treadmill abrasion injury, with the index finger, middle finger, and ring finger being frequently involved. The wound area is generally small, and most of the wounds are deep abrasion injuries.

Behavior characteristics of abrasives for improving surface integrity in magnetic pin polishing

Since surface finishing is a necessary process to meet various requirements in a manufacturing stage, numerous finishing method have been studied to improve the surface integrity. In particular, use of magnetic energy has been developed due to benefits for complex surface. However, it is an immature technique for non-ferrous materials due to low permeability, and also it is the time-consuming process for large area, which is caused be low finishing rate. To overcome drawbacks of magnetic finishing methods, this study suggests a magnetic pin polishing (MPP) process affected by combined magnetic and kinetic energy. According to analysis of experimentation, surface roughness improved due to pin’s dynamic motion which is generated by magnetic force and torque in presence of the magnetic field.

Abrasive wear characteristics and microstructure of Fe-based overlaid ploughshares in different field conditions

In the present research, two different Fe-based claddings, namely SZ (Fe–Cr, Fe–33.37Cr–3.83C) and ZK (Fe–Mo, Fe–8.18Mo–4.5Cr–0.65C) were overlaid on EN-42 steel substrate by Manual Metal Arc Welding (MMAW) process with an aim to enhance the abrasive wear characteristics of the steel. The microstructural and abrasive wear behavior of overlaid samples was investigated in comparison with bare steel (EN-42) in actual field conditions at two different moisture levels (0–3% and 14–17%). Optical microscopy, scanning electron microscope (SEM), X-ray diffraction (XRD), and hardness testing were performed to characterize the microstructural and mechanical properties of bare and overlaid steel samples. The effect of moisture content on abrasive wear resistance of tillage tools and tillage quality has also been evaluated. The results revealed that the variables such as carbide shape, size, distribution, and matrix structure of hardfacing influence the wear resistance of hardfacings. The SZ alloy showed higher abrasive wear resistance than ZK alloy due to the formation of M23C6 and M7C3 carbides in the hardfaced layer. The moisture content of the soil also affected the abrasive wear resistance of the substrate and different hardfacings materials, which in turn influence the tillage efficiency of the tool. The wear rate of bare and overlaid ploughshares is almost 3 times higher in dry field conditions (0-3% moisture) as compared to moist conditions (14–17%). The wear resistance indices (WRI) for SZ and ZK overlaying were found to be 1.85 and 1.48 respectively for low moisture conditions, and 1.9 and 1.54 for the moist condition.

A Comparison of Adhesive Wear with Three-Body Abrasive Wear Characteristics of Graphitic White Irons Designed for Metal-to-Metal Wear Systems

Frictional heat-induced severe adhesive wear has been limiting the lifetime of metal-to-metal wear systems for many years. Five graphitic white irons were previously designed and produced to introduce flake graphite into white iron, with the goal to expedite heat dissipation and reduce the frictional heat effect. This paper focused on the graphite addition effect on adhesive wear resistance for graphitic white irons and its comparison with abrasive wear. Adhesive wear resistance was assessed with a block on ring apparatus in accordance with ASTM G77. An empirical model was formulated to quantitatively evaluate graphite additions’ effect on the adhesive wear resistance. The model indicated that 1 vol.% graphite addition had the same effect as a hardness increase of 2.66 HRC, which was a 14% higher contribution than previously observed for three-body abrasive wear of the same alloys studied following ASTM G65. The improved wear resistance was related to an increased thermal diffusivity of the composite microstructure, and the surface lubricating effect of graphite.

Abrasive Segmentation of Multiple Diamond Images Based on Secondary Morphological Reconstruction

Faced with a lot of noise problems in diamond abrasive image segmentation under complex background, a segmentation method of diamond abrasive images is proposed based on secondary morphological reconstruction. The method of histogram equalization was firstly used to pre-process the original image, which aim is to improve the image by adjusting the global contrast, and an appropriate structural element is constructed to carry out to determine abrasive size by using the morphological smoothing operation; Secondly, the first morphological reconstruction is carried out to further virtualize the complex background and clear garget abrasives by using the geodesic corrosion operation; Then, the second morphological reconstruction is carried out by calculating geodesic expansion operation. Combined with the local extreme value processing of the image, each target abrasive area can be obtained. Finally, the segmented target abrasive area is used to extract the multiple abrasives from complex background. It is found that the complex background noise can be readily eliminated by the proposed method, and the abrasives in the image can be well segmented. The results show that segmentation boundary is clear, without background noise, and the segmentation region is significant. The extracted diamond abrasives can be used for advanced image analysis such as abrasive characteristics and abrasive identification.