Similar Hardness Research Articles

Investigation of various plant protein ingredients for processed cheese analogues: physical properties and microstructure compared with milk proteins

Abstract This study evaluated various structural and physical properties of several plant proteins in the context of processed cheese analogues (PCAs). A total of 9 plant protein sources were selected to formulate PCA samples. The samples were processed at 90 °C for 10 min using either a rapid visco analyzer or water bath for different tests. Rheological analysis revealed that PCA samples formulated with plant proteins all exhibited solid-like behaviour. PCAs containing legume proteins had a higher storage modulus (G’) than that of rennet casein (RC) cheese samples, while canola protein samples showed the lowest G’ values. Zein-based PCA had the highest hardness and chewiness but softened when subjected to heat during the stretchability test. In contrast, PCAs containing chickpea, mung bean, or pea proteins exhibited similar hardness to RC-based cheeses but had poorer springiness, cohesiveness, and resilience. Plant protein-based PCAs also lacked melting and stretchability properties due to the absence of a continuous protein network. When ranking all proteins in PCAs based on viscosity, rheological, and textural properties, lentil protein scored the highest, followed by hemp and quinoa proteins, performing most similarly to casein protein. The presented comparison of different plant proteins in PCAs provides valuable insights for cheese analogue development.

The Influence of Rubber Hysteresis on the Sliding Friction Coefficient During Contact Between Viscoelastic Bodies and a Hard Substrate

This paper describes research aimed at the experimental determination of the influence of rubber hysteresis on the friction coefficient between rubber samples for making soles and granite tiles. In the experiments, four types of shoe rubber with similar hardness and different hysteresis properties and two granite tiles with different roughnesses (smooth and anti-slip) were used. The determination of rubber hysteresis was carried out experimentally on a uniaxial testing machine. The friction coefficient was measured using a device specially developed for this type of test, which was based on the pulling force method, while the measurement conditions were based on the EN 13893:2011 standard. The friction coefficient was measured at two different speeds, 50 mm/s and 300 mm/s, with different surface conditions. Using regression analysis and the Taguchi method, the data obtained from the experiments were analyzed to determine the influence of parameters on the friction coefficient. The experimental research shows that different rubber mixtures with the same or similar hardness could have different hysteresis properties but also different friction properties.

Improvement of the Corrosion Resistance for Martensitic Stainless Steel By Laser Thermal Processing

IntroductionStainless steels are widely used as medical devices. Martensitic stainless steels can be hardened by quenching. Therefore, in the medical field, martensitic stainless steels are mainly used for knives and surgical instruments with cutting edges. However, carbon, a necessary additive for the hardenability of martensitic stainless steels, reduces their corrosion resistance. Therefore, it is theoretically difficult to achieve both high hardness and high corrosion resistance in stainless steels. To ensure the safety and longevity of devices made of martensitic stainless steels, improved corrosion resistance is required. In this study, an improved corrosion resistance of martensitic stainless steels was tried by laser thermal processing. Rapid heating and rapid cooling process by laser irradiation is expected to suppress the formation of corrosion-inducing (MnS) inclusions. The effects of the laser thermal processing on the corrosion resistance, microstructure, and hardness of the specimen surface and substrate layers were investigated.Materials and methodsThe specimens were commercially available type 420J2 stainless steel plates. Each plate was irradiated with a laser of 10 mm diameter at a rate of 100 cm min-1. The irradiation powers were 950 W, 1100 W, 1650 W, 2000 W, 2500 W, 3000 W, 3500 W, and 4000 W. The surface and cross-sectional metallography and inclusions of the laser-irradiated specimens were observed and analyzed using OM, SEM/EDS, and EBSD. Corrosion resistance was also evaluated by anodic polarization tests. A mixed aqueous solution of 0.1 M Na2SO4 and 0.585 M NaCl at 297 ± 3 K was used as the test solution. A Pt plate and a Ag/AgCl (saturated KCl aqueous solution) electrode were used as the counter and reference electrodes, respectively. The potential sweep rate was 20 mV min-1.Results and discussionThe specimens surface after the laser thermal process were observed. The surfaces of the specimens processed at 950 W or 1100 W were smooth, while those processed at 1650 W or higher had a wavy shape. The specimens with exposed cross sections were chemically etched. A light-colored area on the surface layer, and a dark-colored area around and inside the surface layer were formed. The light-colored area is the layer whose microstructure has been changed by laser irradiation. In addition, the light-colored area of the specimens processed at 1650W or higher were divided into two parts. Defined as phase A (upper part of light-colored area), phase B (lower part of light- colored area), and phase C (dark-colored area), in order from the surface. The main phase of the unprocessed specimen is ferrite with a small amount of residual austenite. EBSD and XRD results indicated that the main phase of phase A is martensite with some austenite phase. Additionally, Vickers hardness of phase A significantly increased compared to the unprocessed specimen. This result confirms that phase A is a martensitic phase, indicating that rapid heating and rapid cooling by laser irradiation caused the martensitic phase to form. Corrosion resistance of phase A layer was better than unprocessed specimen. The pitting potential of the phase A layer increased with irradiation power, with the highest value at 3500 W. Some cracks appeared on the surface of the specimen processed at 4000W. These cracks are the reason for the lower corrosion resistance. Inclusions consisting of spherical Si oxides smaller than 1 µm were observed in the microstructure of the phase A layer; no MnS inclusions were observed. The presence of fine spherical Si inclusions and the wavy surface suggest that phase A was formed by melting and then rapidly solidifying due to laser irradiation. MnS was solidly soluble in the matrix phase by melting, and its formation was inhibited by rapid solidification. As a result, MnS inclusions in phase A were reduced and the corrosion resistance of phase A was improved. On the other hand, phase C showed similar hardness and corrosion resistance to the unprocessed specimen, and there was no difference in corrosion resistance depending on irradiation power. Thus, although phase C was heated by the laser, no melting or microstructural transformation occurred. In other words, laser thermal processing does not degrade the properties of the inner layer. The corrosion resistance, hardness, and microstructure of phase B were intermediate between those of phases A and C.Conclusion420J2 stainless steel was subjected to laser thermal process at various power to evaluate microstructure and corrosion resistance. Laser thermal process suppressed the formation of corrosion-induced inclusions in the surface layer, and the surface layer transformed to martensitic structure. Laser thermal processing succeeded in modifying the surface to have both high corrosion resistance and hardness. Figure 1

Preparation and characterization of sago/iota-carrageenan microgels as food thickener in texture modified food

An increasing number of older populations with swallowing difficulties need specialized diets with easy-to-chew and safe swallowing characteristics. Texture modification using a thickener is usually used to obtain the desired texture, which helps in lowering the risk of aspiration. Microgels usage to modify the texture and rheology of liquid and pureed foods has been an area of interest in the food industry for many years. Therefore, this study aimed to produce sago starch and ι-carrageenan based microgels with functionality as food thickeners. Different concentrations of ι-carrageenan (25%, 50% and 75%) were added into sago starch dispersion and then fabricated using ultrasound treatment followed by spray drying process. A commercial dysphagia thickener that is normally used at medical institutions and nursing homes was also included as a reference. Microgels with increasing ι-carrageenan concentration showed variation in behaviours during rheological and textural measurements. Rheological tests revealed that sago/ι-carrageenan microgels exhibited a predominant elastic behaviour, with G′>G″ within the frequency range. Texture profile analysis (TPA) suggested that the sample with 2.0 g of sago starch and 2.0 g ι-carrageenan, MS50, produced samples with similar hardness, springiness, and cohesiveness to the reference sample. Overall, sago/ι-carrageenan microgels have shown a potential to be used as an alternative thickener as it provides low adhesiveness and more elastic behaviour which is considered safe-to-swallow food, especially for elderly with swallowing difficulties.

Contour maps of mechanical properties in ternary ZrB2-TiC-SiC ceramic system

Monolithic ZrB2, ZrB2-SiC, ZrB2-TiC and ZrB2-SiC-TiC were fabricated by hot pressing. Contour maps depicting grain size and mechanical properties were generated on the ZrB2-SiC-TiC ternary diagram through experimental data and software fitting. These visual representations effectively establish the relationships between chemical composition and material properties, despite the similar high hardness of three main compounds. Notably, the average grain size of ZrB2-SiC-TiC is significantly reduced by an order of magnitude compared to monolithic ZrB2. Both strength and hardness exhibit a strong correlation with grain size, while the elastic modulus demonstrates insensitivity to microstructure changes. The evolution of toughness proves to be complex.

Wear and damage behaviors of wheel-rail with different material matchings under various sand deposition densities of rail top in desert environments

In desert environments, the phenomenon of sand particles depositing on the rail top and contaminating the wheel-rail interface is common because the railway is an open system. This work aimed to investigate the wear and damage behaviors of wheel-rail with different material matchings under various sand deposition densities of rail top in desert environments. The results showed that as sand deposition density increased, adhesion coefficient first decreased sharply and then increased slowly, and finally decreased slowly. It was caused by the combined effect of sand solid lubrication, oxide solid lubrication, and surface roughness of wheel and rail. The oxidative wear increased first, peaking at about 0.2 g/m2, and then decreased, whereas the fatigue wear decreased consistently. For wheel and rail materials with similar hardness, the wheel-rail material matching with high carbon content exhibited excellent anti-wear and anti-fatigue performances. The wear and damage of wheel and rail were relatively mild when the sand deposition density was lower than 0.4 g/m2.

Exploring the hardness-independent wear behavior of typical wear-resistant materials under dynamic and static conditions

In this study, three types of wear-resistant materials including high-chromium cast iron (HCCI), medium-chromium cast steel (MCCS), and low-chromium cast steel (LCCS), with similar macroscopic hardness but distinct microstructures and impact toughness have been prepared. The wear behavior of these three materials under different loads were investigated by impact wear experiments under dynamic load and three-body wear experiments under static load. The results revealed that the almost fully martensitised MCCS had the least mass loss under low dynamic impact load wear conditions. The brittleness associated with large carbides intensified with increasing impact load, culminating in a significant reduction in the impact wear resistance of HCCI. The residual austenite rapidly transformed into martensite, thereby effectively improving the wear resistance of the LCCS. Comparatively, the experimental steels were all characterized by fatigue wear of the abrasive on the material surface under static wear conditions at low loads and showed similar wear resistance. Conversely, the large carbides demonstrated superior wear resistance under conditions of high static load, and HCCI had the best wear resistance.

Investigation of the effect of current density and ZrO2 bath concentration on electrodeposited Ni-P/ZrO2 composite coatings

In this study, Ni-P/ZrO2 nanocomposite coatings were deposited on St-37 steel substrates using the electroplating method with varying ZrO2 concentrations and current densities. To investigate the effects of electrolyte components and current density on coating properties, analyses were performed regarding microhardness, wear performance, and surface morphology. As a result of the analyses, it is observed that different bath concentrations and current densities significantly affect properties such as morphology, hardness, and wear performance. It is seen that the surface morphologies of the obtained coatings are generally smooth, but it is understood from the optical images that the surfaces of all nanocomposite coatings are rougher. While adding ZrO2 nanoparticles to the main matrix increases microhardness by approximately 40% compared to pure nickel, a similar but higher hardness value was obtained with the increase in current density. When examined in terms of wear performance, an average friction coefficient value of 3.15 times higher than that of pure nickel nanocomposite coatings was obtained.

The effects of different strengthening treatments on wear performance of ZL109 aluminum alloy at high temperature

Enhancing strength or hardness is a widely employed strategy to improve wear resistance of ZL109 aluminum alloy at elevated temperatures. This study aimed to investigate the effects of various strengthening treatments on the wear performance of ZL109 aluminum alloy. Three strengthening methods, namely structural refinement, strain hardening, and precipitation strengthening, were employed to achieve a similar hardness level. Subsequently, the wear tests were conducted using a reciprocating ball-on-disk tribometer under different temperature conditions. The results showed that all the strengthening samples exhibited a similar wear rate (approximately 7.0 × 10−4 mm3/N·m) at room temperature. However, at 250 °C, the precipitation strengthening sample performed best with a wear rate of 1.32 × 10−3 mm3/N·m, followed by the strain hardening and structural refinement samples (approximately 1.7 × 10−3 mm3/N·m). This superior performance was attributed to the precipitation phase, which could effectively maintain material strength through dislocation pinning. By contrast, dynamic recovery and recrystallization behavior weakened the effectiveness of strain hardening, while crystal growth diminished the efficacy of structural refinement. In addition, the wear mechanisms transitioned from abrasion to adhesion and slight oxidative wear as the temperature increased.

Thermal features and its effect on the properties of AISI 4140 fabricated by conventional and extreme high-speed laser material deposition

The extreme high-speed laser material deposition (EHLA) process has the potential to enable additive manufacturing for mass production by overcoming the limitations of slow scanning speed in conventional laser material deposition (LMD) processes. Thermal features are the key factors to link process and properties. A sound understanding of process-thermal-property relationships is essential for performance control and process optimization of a deposited component. In this study, we studied the thermal characteristics within a single layer and among layers for continuous processing using the numerical method, and reveal the mechanism of microstructure and hardness changes of AISI 4140 material formed by EHLA and LMD processes through the analysis of thermal properties and temperature history results. The grain size and hardness evolution for both processes during single-layer cladding and continuous forming processes were investigated. The results revealed that the grain refinement effect in continuous LMD processing is stronger than that in EHLA process (from 30.0 μm for single layer to 3.2 μm for multi layers vs. from 18.6 μm for single layer to 2.2 μm for multi layers). Similar hardness values were obtained by LMD and EHLA processes, with mean values of 511 HV and 472 HV, respectively. The yield and tensile strengths of EHLA were superior to the conventional cast material, but inferior to those of the conventional material quenched and tempered at lower temperatures. The enhanced tensile results of EHLA process were found similar to those prepared through conventional method with quench and tempering at 600 °C.

Production of complex microchanneled parts of ZrB2-MoSi2 ultra-high temperature ceramics by freeze casting and pressureless spark plasma sintering

A novel approach for manufacturing complex parts of ultra-high-temperature ceramics (UHTCs) is proposed, combining freeze casting with pressureless spark plasma sintering (SPS). With the aid of MoSi2 sintering additive (15 vol% or more), this combination enables the production of fully dense ZrB2-based UHTC parts at 1900 °C. Producing complex-shaped samples including an intricate network of internal microchannels seems feasible, by using additive manufacturing techniques in the production of templates for the external silicone mould and the internal microchannel network to be used during the freeze casting process. Although defects are prone to occur either during freeze drying, due to thermal stresses arising from the expansion mismatch between the internal resin template and the ceramic preform, or during the resin burn-out or SPS cycles, the resulting samples exhibited a fully dense microstructure and similar hardness (17 ± 1 GPa) as the bulk material. Thus, the proposed approach shows promise in the production of arbitrarily complex-shaped UHTC parts that may find application in numerous industrial sectors including aerospace, aviation, and energy generation and storage.

The improvement of dry sliding tribological properties by designing nano-primary cementite in bainitic/martensitic matrix microstructure in hypereutectoid PM components

The production of nano-sized primary cementite in bainite/martensite matrix (NCBM) microstructure was designed to improve the dry sliding wear properties of high carbon PM parts. A different heat treatment cycle was carried out for the production of novel the NCBM microstructure. High purity iron powder 1.5 wt%. natural graphite powder was added and it was compacted in the form of a dry sliding wear test specimen in a mold and sintered at 1200 °C in a pure Ar gas atmosphere. The novel NCBM microstructure in the PM material was produced by quenching at 950 °C, then annealing at 600 °C for 12 min, then quickly cooling from 730 °C to 250 °C in a salt bath and keeping it isothermal for 100 s. The friction coefficient of materials with NCBM microstructure was less than other samples. It was found that while the wear coefficient were higher in the tempered martensitic microstructure sample having higher hardness, they were less than in the sample having bainitic/martensitic microstructure with similar hardness.

Optimum Insole Hardness for Attenuating Peak Plantar Pressure Under Simulated Loading Scenarios

To provide optimal cushioning capacity, an in-depth understanding of the biomechanical interactions between the foot and therapeutic insoles is mandatory. The goal of this study was to quantify the hardness of plantar soft tissues (PSTs) and investigate the potential association between the hardness of PSTs and the optimum hardness of insole materials. The authors tested the hardness of PSTs in eight plantar regions by using a durometer to examine 30 cadaveric feet. The effects of hardness and loading magnitude on peak plantar pressure at the heel–insole interface were investigated in simulated weight-bearing tests. Significant effects of insole hardness on the cushioning capacity were observed among different loading conditions (p<0.01). No significant association was found between the hardness of individual-specific PSTs and optimum cushioning materials (p<0.05). This study provides quantitative data on PST hardness, and this knowledge may be valuable for developing insole materials with similar hardness to the PST in order to achieve optimum pressure relief under the foot.

Strengthening mechanism of friction-stir welded Fe-17Mn alloy

In present study, the strengthening mechanism of friction-stir welded Fe-17Mn binary alloy was quantitatively investigated by means of the electron microscopic observation in stir zone center and the dislocation-based constitutive equation. As the rotation speed increased from 440 to 760 rpm, both fraction of thermal ε martensite and prior γ austenite size were elevated due to the severely frictional heat, whereas the dislocations were annihilated. Though different microstructural feature of welds, the stir zone center had similar hardness and yield strength regardless of rotation speed. It was because of notable increase in ε martensite hardening as well as marginal decreases in hardening in grain boundary and dislocation with increasing rotation speed.

AMPK activation by dietary acadesine improves fillet texture in large yellow croaker (Larimichthys crocea) fed a linseed oil-based diet

The impacts of AMP-activated protein kinase (AMPK) activation by dietary acadesine (AICAR) on growth performance and muscle quality of large yellow croaker (Larimichthys crocea) fed a linseed oil-based diet (LO) were investigated by a 56-day feeding trial in this study. Fish (initial weight: 92.24 ± 0.30 g) were fed fish oil-based diet (FO), LO or LA (LO diet supplemented with 150 mg kg−1 AICAR) with three replicates of each treatment. Results indicated that weight gain rate and specific growth rate (SGR) were significantly decreased in the LO and LA groups than those of the fish fed FO, while the opposite was true for the feed conversion ratio. Moreover, the SGR of fish fed LA was significantly lower than that of the LO group. Dietary linseed oil and AICAR significantly lowered muscle eicosapentaenoic acid and docosahexaenoic acid contents. Furthermore, the LO group showed significantly lower fillet hardness, chewiness and pH, while higher lipid loss than those of the FO group. However, the FO and LA groups had similar fillet hardness, lipid loss and pH. Compared with the fish fed FO and LA, the LO group possessed significantly lower p-AMPK protein level and p-AMPK/AMPK ratio in muscle. The phosphorylation of TOR protein and the ratios of p-TOR/TOR and p-S6/S6 were significantly decreased in muscle of the LA group than those of the fish fed FO and LO. Meanwhile, totally replacing fish oil with linseed oil inhibited the AMPK/SIRT1/PGC-1α pathway, changed myofibre characteristics (e.g., density, diameter and type of myofibre) and raised the expression of genes or activity of enzyme related to anaerobic metabolism in fish muscle. Dietary AICAR activated AMPK/SIRT1/PGC-1α pathway, restored myofibre characteristics and promoted aerobic metabolism-related genes expression in muscle to some extent. In conclusion, total substitution of dietary fish oil with linseed oil reduced growth, feed utilization and nutritive value of large yellow croaker. And high level of dietary linseed oil induced softer texture and poorer liquid holding capacity (LHC) of muscle, which may be ascribed to the myofibre characteristics changed by linseed oil through depressing muscle AMPK/SIRT1/PGC-1α pathway. Inclusion of AICAR in a linseed oil-based diet improved fish muscle hardness and LHC, which may be relevant to the activated muscle AMPK/SIRT1/PGC-1α pathway and restored myofibre characteristics by AICAR. Notably, dietary AICAR could inhibit TOR pathway by activating AMPK in muscle, which may be responsible for the further decreased SGR of fish fed a linseed oil-based diet.

Effect of Interlayer on Flatness and Adhesion of Aerosol-Deposited Yttrium Oxide Coating.

In this study, Y2O3 coating is used as an interlayer between Al2O3 substrate and a ceramic coating; this is in order to minimize the morphological distortion produced by a single deposition of the ceramic coating on the Al2O3 substrate, which is performed using the aerosol method. The interlayer coating, which comprises the Y2O3 phase, is deposited on the Al2O3 substrate using an e-beam evaporator. The crystal structure of the powder that was used to process the coating is identified as cubic Y2O3. In contrast, the crystal structure of the top-coating layer and interlayer indicates the presence of two kinds of Y2O3 phases, which possess cubic and monoclinic structures. The single Y2O3 coating without an interlayer exhibits microcracks around the interface between the coating and the substrate, which can be attributed to the stress that occurs during aerosol deposition. In contrast, no cracks are found in the aerosol-deposited Y2O3 coating and interlayer, which show a desirable microstructure. The single Y2O3 coating and the Y2O3 coating with an interlayer exhibit similar hardness and elastic modulus values. Nevertheless, the Y2O3 coating with an interlayer exhibits a higher level of adhesion than the single Y2O3 coating, with a value of 14.8 N compared to 10.2 N.

Oxidation resistance and thermal stability of (MoZrHfTaNb)-Si-B coatings deposited by HIPIMS method with different Ar pressure

The influence of argon pressure on the structure, mechanical characteristics, oxidation resistance, and thermal stability of (MoTaNbZrHf)-Si-B coatings deposited by HIPIMS method using a composite target based on high-entropy (MoZrHfTaNb)Si2 silicide and (MoZrHfTaNb)B2 boride was studied. Coatings deposited at Ar pressure of 0.1–0.2 and 1.3–2.2 Pa had a dense, defect-free structure. Increasing the Ar pressure to 37–42 Pa led to the formation of a coating with a columnar structure, while, according to X-ray diffraction and transmission electron microscopy, all coatings were amorphous. Increasing the Ar pressure from 0.1 to 0.2 to 37–42 Pa led to a magnifying the growth rate of coatings in 2.5 times. All coatings were characterized by a similar hardness of 14–15 GPa. The elastic modulus and elastic recovery decreased from 196 to 178 GPa and from 40 to 34 % when the argon pressure increased from 0.1 to 0.2 to 37–42 Pa, respectively. The coatings successfully resisted oxidation at temperatures of 1100 °C and 1300 °C. The protective properties of the coatings are due to the formation of a dense oxide film based on a-Si:B:O amorphous phase with crystallites of the m-HfO2, m-ZrO2, m-Nb2O3, o-Ta2O5, t-ZrSiO4 and t-HfSiO4 phases. Heating in a TEM column showed that the coating deposited at an Ar pressure of 0.1–0.2 Pa crystallizes immediately upon reaching a temperature of 700 °C with the release of predominantly the h-MoSi2 phase. Crystallization of the coating obtained at an Ar pressure of 37–42 Pa also occurs at 700 °C, but only during long-term exposure and is accompanied by the precipitation of the h-Ta5Si3 and t-Nb5Si3 phases. Thus, it has been shown that by increasing the gas flow rate, the productivity of sputtering in the HIPIMS mode can be increased without a significant loss in hardness, oxidation resistance and thermal stability of coatings.

Extraction of Lipids and Functional Properties of Defatted Egg Yolk Powder Obtained Using a One-Step Organic Solvent Lipid Extraction Process.

A one-step organic solvent lipid extraction method was used to separate lipids from spray-dried egg yolk. Organic solvents tested were chloroform:methanol (CM, 2:1, v:v), methyl-tert-butyl ether (MTBE), or hexane:isopropanol (HI, 3:2, v:v). The resulting defatted egg yolk powder had between 21 and 30% more protein and between 22 and 25% less lipid than the initial spray-dried egg yolk powder (p < 0.05). The solubility of the powder decreased from 20% to 4% (p < 0.05) when CM was used as the organic solvent, likely due to protein denaturation by the chloroform. Gels made from MBTE and HI-extracted protein concentrates had similar hardness (p > 0.05) and were both harder than gels made using the initial egg yolk powder (p < 0.05). MTBE gels were springier, more cohesive, and gummier (p < 0.05) with similar resistance to the initial egg yolk powder (p > 0.05). The results of this study showed that the functionality of the protein in the defatted egg yolk powder was best retained when MTBE was used as the lipid extraction solvent.

Use of threaded cylindrical pin tools to reduce macroscopic defects in dissimilar welded joints of AA7075-T6 and AZ31B alloys by the FSW process

The continued increase in greenhouse gas emissions has had dire consequences for the global climate. In order to reduce such emissions, several efforts have been made by researchers in the transport sector, such as the development of electric motorization, the development of hybrid engines, the use of biofuels and the use of light alloys. The use of light alloys such as aluminum and magnesium in vehicles can reduce the emission per kilogram of vehicles drastically, however, it is still necessary to develop effective and more agile methods of the dissimilar joints of these materials. Some authors have studied the friction stir welding of AZ31B magnesium alloys and AA7075-T6 aluminum alloys in order to determine better process parameters to enable this bond, however, few articles have been published in order to evaluate the influence of tool geometry on such properties. In this sense, this article aims to evaluate the influence of friction welding tool pin geometry as smooth cylindrical pin, threaded cylindrical pin, conical and hexagonal pin configurations in the formation of the mixed zone of welds manufactured by the FSW process. For this purpose, AZ31B and AA7075-T6 alloys were welded by FSW with welding speed of 75 mm/min, tool rotation speed of 565 rpm, offset of 0.5mm and inclination of the tool geometry in relation to the plates to be welded of 3º, the joints were evaluated for their macro and microstructures and Vickers hardness with a load of 100 gf. It was possible to observe that the joints welded with the threaded cylindrical pin tool presented stir zones free of macroscopic defects, similar hardness values for the four tools studied and the presence of a thin layer of intermetallics between TMAZ and SZ on the AZ31B side.

Investigation of thermal effects in bulk oxide chemical mechanical polishing

Bulk oxide polishing occupies a substantial portion of time to achieve surface planarization in semiconductor manufacturing. Recently, thermal management has emerged as a critical issue in the polishing process. Fundamental research on thermal effects in oxide film polishing is essential for optimizing both the thermal management system and the polishing process itself. Experiments indicate that friction force, significantly influenced by wafer and retainer ring pressures as well as slurry species, plays a major role in determining polishing temperature, more so than slurry flow rate. An important finding is the temperature-dependent behavior of slurry particles, which generally reduce in size and concentrate more at higher temperatures, with aggregation starting at around 80 °C. High-temperature slurry deteriorated pad properties but enhance oxide film surface hydrolyzation. During a 60-s polishing process, the slurry temperature exhibited the maximum removal rate at 60 °C for fumed silica polishing, while for calcined ceria, the highest removal rate was observed at 20 °C. Pad B at ambient temperature, having similar hardness to Pad A at 60 °C, reduced the oxide film removal rate by 31.82 % for fumed silica and 40.94 % for calcined ceria. This indicates that pad hardness has a more pronounced effect on polishing with calcined ceria slurry.