Process optimization and removal of phenol formaldehyde resin coating using mechanical erosion process

Consumption of coated abrasive discs in various automobile and pipe fitting application is increasing, due to its good surface finish. Coated abrasive disc consists of single layer of abrasive grain bonded to a fibre backing. The major portion of the disc is comprised of fibre backing. But the sustainability of the fibre backing is low and is dumped as waste after usage. The present work deals with the removal of resin coating and recovery of fibre backing from the spent coated abrasive discs using physical separation process such as sand blasting technique. Initially, the recovery experiment was carried out based on L16 orthogonal array. The factors and levels chosen for the experiments were erodent pressure (0.2, 0.4, 0.6 and 0.8 MPa), erodent size (36, 60, 80 and 120 grit), disc orientation (30, 45, 60 and 75°) and number of times flexing (5, 10, 15 and 20). The experimental result shows that erodent size and erodent pressure have a major impact on recovery of the fibre backing. The surface structure of the recovered backing was analysed using scanning electron microscopy and optical microscopy. The recovered backing was very much useful for the coated abrasive industry as the flexible backing and support material for abrasive grain coating.

Flow accelerated corrosion and erosion−corrosion behavior of marine carbon steel in natural seawater

In this work, flow accelerated corrosion (FAC) and erosion−corrosion of marine carbon steel in natural seawater were electrochemically studied using a submerged impingement jet system. Results show that the formation of a relatively compact rust layer in flowing natural seawater would lead to the FAC pattern change from ‘flow marks’ to pits. The increase of the flow velocity was found to have a negligible influence on the FAC rate at velocities of 5−8 m s−1. The synergy of mechanical erosion and electrochemical corrosion is the main contributor to the total steel loss under erosion−corrosion. The increase of the sand impact energy could induce the pitting damage and accelerate the steel degradation. The accumulation of the rust inside the pits could facilitate the longitudinal growth of the pits, however, the accumulated rusts retard the erosion of the pit bottom. The erosion and corrosion could work together to cause the steel peeling at the pit boundary. The steel degradation would gradually change from corrosion-dominated to erosion-dominated along with the impact energy increasing.

Provenance controls on volcaniclastic beach sand: example from the Aeolian Archipelago, Mediterranean Sea

Sand and sandstone composition of volcanic origin may be clues to the provenance of the sediments and sedimentary rocks. Volcaniclastic provenance studies contribute significantly to unravel the sediment generation and provenance under investigation that in the Aeolian archipelago comprise preserved units of outcrops dominated by lava flows intercalated with air fall tephras as source rocks. The aim of this paper is the study of the petrographic composition and the textures of beach sands that may be used as a guide for the interpretation of provenance and origin of beach sand(stone)s rich in volcanic debris transported into deeper water. The composition of Aeolian beach deposits defines a single immature petrofacies with a high amount of unweathered glass and mafic minerals. Panarea island is dominated by dacites and new grain categories have been proposed to discriminate this provenance. Surface processes such as mechanical erosion (mass wasting and surface runoff) produce an overestimation of mafic components, with respect to the felsic ones in the beach sand fraction.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5608950

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.

Effect of Organo Montmorillonite Nanoclay on Mechanical Properties Thermal Stability and Ablative Rate of Carbon fiber Polybenzoxazine Resin Composites

Organo-Montmorillonite (o-MMT) nanoclay added polybenzoxazine resin (type I composites) were prepared with varying amounts of clay (0, 1, 2, 4 and 6 wt %). Clay dispersion, changes in curing behaviour and thermal stability were assessed in type I composites. Findings from these studies of type I composites were used to understand thermal stability, mechanical, and mass ablation rate behaviour of nanoclay added carbon fiber reinforced polybenzoxazine composites (type II). Interlaminar shear strength and flexural strength of type II composites increase by 25% and 27%, respectively at 2 wt% addition of clay. An oxy-acetylene torch test with a constant heat flux of 125 w/cm2 was used to investigate mass ablation rate of type II composites. The ablation rate has increased as the weight percentage of clay has increased. This is contradicting to type I composites with up to 6 wt% clay and type II composites with up to 4 wt% clay, which have improved thermal stability. The microstructure of the ablated composites was examined using scanning electron microscopy. Increased ablation rates are due to the reaction of charred matrix with nanoclay, which exposes bare fibers to the ablation front, resulting in higher mechanical erosion losses.

Temporal evolution of impact-atmosphere-interior interactions in terrestrial planets

<p>We constructed a system of parameterized or semi-analytical representations of impact-related processes such as crater formation, atmospheric erosion, and melt production due to the direct effects of the impact as well as the long-term thermal effects triggered in the mantle by very large impacts in order to model how impactors of different types and a large range of sizes affect the CO<sub>2</sub>-H<sub>2</sub>O atmosphere and the interior of a terrestrial planet similar to Mars, Venus, or the early Earth. Mass fluxes of carbon dioxide and water between the impactor/outer space, the atmosphere, and the interior of the target planet are calculated in order to assess under which conditions atmospheres and interiors are depleted or enriched by processes related to impacts, melting/magmatism on different time scales, or weathering.</p> <p>The impactor flux onto a planetary target is a stochastic process in terms of time, magnitude and location, which we describe with a size-frequency distribution of impactors and a cratering chronology. The temporal aspect, in combination with the complexities of the various effects of a single impact, cause the evolution to depend on its own history. In the absence of unique information about the impact sequence of a target, the evolution should therefore not be uniquely determined by cratering statistics, and the possible paths are expected to vary within a certain range. Thus, we aim to deduce a range of evolutionary paths for the volatile content of the atmosphere and, within limits, of the interior.</p> <p>We consider rocky S-type and icy-rocky C-type asteroids as well as comets, covering a range of impactor-target density contrasts from about 1/6 to about 4/5 as well as a range of (absolute) impact velocities from a little less than 10 to almost 65 km/s. Impactor size ranges from 1 m to half the planetary radius. Atmospheric (surface) densities cover almost five orders of magnitude, ranging from a few millibars (modern Mars) to 95 bar (modern Venus).</p> <p>With regard to atmospheric effects, there is a fundamental distinction to be made between blast-producing and crater-forming impacts; the boundary that separates these two regimes is mostly defined by the deceleration of the impactor and its resistance to breakup under the ram pressure during its traversal of the atmosphere. The direct effects of the former leave the interior essentially unaffected and interact only with the atmosphere. We use the formalism by Svetsov (2007) to assess the bulk mass transfer and balance resulting from mechanical erosion of the atmosphere and the disintegration of the impactor and estimate the balance for the individual volatiles from estimates of the impactor composition. In crater-forming impacts, there are additional effects that need to be included. Ejecta can contribute to the mechanical erosion of the atmosphere (e.g., Shuvalov et al., 2014) and also produce layers of porous material with a large, reactive surface that can absorb CO<sub>2</sub> from the atmosphere by weathering in the long-term aftermath of an impact. Moreover, they produce a crater that opens up the interior to mass exchange with the atmosphere. A key process in this context is the production of impact melt, which can serve as a vehicle for volatiles between the atmosphere and the interior by either releasing or removing (by dissolution) CO<sub>2</sub> and water, depending mostly on the pressure conditions at the interface; generally outgassing is expected to be more common, but still these two volatiles may behave quite differently. We find that CO<sub>2</sub> is expelled from the melt much more easily than water and will therefore enter the atmosphere under all conditions considered, whereas water may be retained in the melt at high atmospheric pressures. In addition to these common effects, very large impacts cause perturbations at sublithospheric depths and implant local thermal anomalies into the mantle that subsequently turn into upwellings and can cause longer-term magmatism and the local degassing from the deep interior.</p>

Synthesis of New Fixings of Mobile Sands

The issues of the synthesis of a water-soluble polymer preparation, which can find application in agriculture as a structure-forming agent of soils and mobile sands to prevent water, wind, mechanical erosion, increase fertility, moisture absorption, moisture retention, consolidation of soils, dumps, and mobile sands to eliminate negative effects on the environment. Maleic acid and acrylamide were chosen as monomers for the copolymerization reaction, and potassium persulfate was chosen as the initiator. As it turned out, an increase in the concentration of the initiator from 0.01 to 0.05% (by weight of monomers) promotes an increase in the rate of the polymerization process, maintaining its value for a longer time, reducing the time of this process from 7.0-6.5 to 5, 5-6 hours. In this case, the yield of the polymerization reaction increased exactly from 81.2 to 96.0% for the reaction with the ratio of starting materials 1: 5. When a small amount of alkali is introduced into the reaction mixture, high molecular weight polymers can be obtained. In this case, the yield of the process increases, and the reaction time is reduced by 2-3 hours. Analysis of the kinetics of fixing processes using synthesized and various other reagents, as well as changes in the plastic strength of sands, showed the dependence of the conditions of penetration of the fixer with the formation of a free flow in space under the influence of gravitational or capillary forces on the type of binding agent and on the composition of the sand itself.