Increase In Hardness Values Research Articles

Modification Structure and their Effects on Physical Properties of Tin Based Lead Free Solder Alloys for Industrial Applications

Soldering properties such as melting temperature and wettability of tin-zinc alloy improved after adding different alloying elements such as indium, aluminum, cadmium and bismuth. Decreasing zinc content (Sn91Zn9) up to 4% (Sn96Zn4 alloy) increased corrosion resistance from -0.847 to -0.530 and decreased corrosion rate from 51.84 to 7.705 mpy. Microstructure of tin-zinc alloy changed with increasing hardness value of it after adding alloying elements. Tin-zinc alloys have lower melting temperature compared to Sn95Sb5, Sn96.5Ag3.5 and Sn99.3Cu0.7 alloys. The Sn90Zn4Bi6 alloy has beast solder properties for electronic industrial applications.

Improvement of Mechanical Behavior of FSW Dissimilar Aluminum Alloys by Postweld Heat Treatments

AA6262 and AA5456 alloys are welded through friction stir weld (FSW) with process parameters of tool speed of 1200 rpm, welding speed of 25 mm/min, and tool angle of 3 degree. A cylindrical shape HSS-13 tool is used to perform the welding process To improve mechanical properties of tensile strength (TS), yield strength (YS), elongation%, hardness, and wear behavior, postweld heat treatment was conducted on the FSW sample at different temperatures from 300°C to 500°C. The influence of heat treatment (HT) changes the material characteristics. It is observed that the maximum TS (209 MPa) and YS (178 MPa) are identified when maintaining temperature 350°C on the FSW sample. The reduction in elongation of as-welded joints is entirely improved by HT, and the elongation percentage is almost increased to 5% when increasing temperature on the heat treatment process, and hardness test results exhibited that the increased hardness value (120Hv) is found at HT-300°C nugget zone distance of 0 to 5 mm range.

The Affect of Aging Process on Wear Properties of Al6061/GNP Metal Matrix Composite

In this study, affect of aging on wear characteristics of the nano GNP reinforced Al6061 metal matrix composites. In this scope, the samples were produced by hot press at 500 ℃ temperature under 50 MPa pressure for 30 minutes. The wear characteristics of the composites were determined using the ball-on disc wear test method. The affect of aging on the friction coefficient and wear ratio were investigated. Graphene reinforcement significantly increased the friction coefficient between the stainless steel ball and specimen but aging process lowered the coefficient of friction to a better level. Also artificially aged specimens showed significant increase in hardness values. Key factors are affecting the mechanical performance of the Al based alloy is reinforcement and aging process.

Spark Plasma Sintering of TaN/TiAl Composites: Microstructure and Microhardness Study

Titanium aluminide (TiAl)-based materials have attracted much attention in the aerospace and automobile industries due to their attractive properties. Studying the microhardness of these materials as it relates to the as-sintered and heat-treated state is of interest in this article. TiAl and TiAl-based composites with varying additions of Tantalum nitride (TaN) content (2, 4, 6, 8 wt.%) were prepared by spark plasma sintering technique. The samples were sintered at 1150 °C, 100 C/min, 50 MPa, a dwell time of 10 mins, and fully dense characteristics as their relative densities were above 98 %. The microstructure and microhardness of the sintered samples were examined. Also, the sintered samples' microhardness was evaluated after the heat treatment process at 750 °C. It was observed that the relative density of the composites dropped at 2 and 8 wt.% addition of TaN, while the addition of TaN significantly increased hardness value in the as-sintered and heat-treated condition, from 304 HV to a maximum of 499 HV in the as-sintered state. The microstructures revealed that the reinforcement was segregated to the gamma phase, interlocked by the lamellar colonies.

The Influencing Effect of Silver Nitrate Fillers on the hardness of Flexible Resin

The development of polymer chemically produces alternative materials to polymethyl methacrylate, such as nylon, and epoxy resin, these resins are modified by thermoplastic process, and This Received The disadvantage of acrylic resin is the colonization of microorganism growth of fungi and candida adhesion. This study is designed to evaluate and compared the consequence of silver nitrate fillers reinforcement Accepted flexible acrylic hardness as one of the mechanical properties to find the effect of various concentrations. A (0.1and 0. 2) ml of the filler (silver nitrate) additive to the flexible acrylic. Forty five (45) specimens were prepared for testing in this study. The hardness test was used in this study. The sample of this test was divided into (3) groups (control group) and experimental groups as follows: Group A= (15) specimens without silver nitrate (Control group 0% silver nitrate). Group B= (15) specimens with (0.1 ml) silver nitrate. Group C= (15) specimens with (0.2 ml) silver nitrate. All control and test groups were processed; curred then finished and polished the specimens ready for testing. Shore A test against the concentration of silver nitrate the result of this study showed a high significant increase in the mean value of hardness for control groups to the silver nitrate compared with experimental groups.

Hydration behavior and formation of strätlingite compound (C2ASH8) in a bio-cement based on tri-calcium silicate and mono-calcium aluminate for dental applications: influence of curing medium

BackgroundThe aim of this work was to study the influence of simulated body fluid (SBF) and Pseudomonas aeruginosa (in Mueller Hinton Broth, MHB media) on the hydration reactions, formation of strätlingite (C2ASH8) and morphology of a composite material based on nano-size tri-calcium silicate (C3S) and tri-calcium aluminate (CA) phases. The two experimental phases were prepared in laboratory by firing the required molar ratios of chemically pure reactants by solid-state reactions at elevated temperatures. Investigation of setting time, micro-hardness, pH of immersion solution, X-ray diffraction analysis, infrared spectroscopy, scanning electron microscopy and cytotoxicity were also carried out.ResultsThe results emphasized that the hydrated compounds of C3S phase can partly solve the problem of conversion process through the formation of the more stable and highly mechanical stratlingite hydrate (C2ASH8) plates that results in an increase in hardness values for samples cured in distilled water (DW) at 37 °C. The SBF solution showed more strength loss than those cured in Pseudomonas aeruginosa microbe (MHB) medium bacterial solution. SEM and EDAX analyses emphasized the formation of hydroxyapatite at 37 °C.ConclusionsThe prepared cements are promising for dental application.

Fabrication, microstructural characterization and finite element analysis of functionally graded Al-Al2O3 disk using powder metallurgy technique

In the present work, powder metallurgy technique was employed to fabricate a three-layer functionally graded (FG) disk. The volume fraction of metal-ceramic composition changes radially as layer-1 (100 % Al), layer-2 (95 %Al +5 % Al2O3), and layer-3 (90 %Al +10 % Al2O3). The microstructural investigation was carried out under an optical microscope and SEM (scanning electron microscopy) integrated with EDS, confirming a uniform distribution of reinforcement particles (alumina) in the matrix (aluminum). Interface microstructure indicates a successful fabrication of FGM (functionally graded material) as the transition is uniform in the graded layer without the development of any crack or void at the interface. In comparison to layer-1, the average increase in hardness values was found to be 18 % and 29 % for layer-2 and layer-3 respectively. An increment in hardness was observed in layers where alumina composition is higher. The Archimedes principle was employed to calculate the experimental density of the sample, and the theoretical models were presented to effectively estimate the density of porous FG materials. Furthermore, theoretical models for estimating material properties such as Young's modulus and yield strength of individual layers were proposed on the basis of material composition and particle shapes obtained from the microstructure of FG disk. These material properties were then used in finite element formulation for the application of rotating disk, the validation of which is also proposed. Subsequently, finite element analysis was employed to perform stress analysis on layered FG disk when subjected to centrifugal loading.

A comparative study on friction stir welding of tailor weld blanks

The effect of single-pass (SP) and double-pass (DP) friction stir welding (FSW) on metallographic and mechanical properties of joints was investigated in this study. Uniform temperature distribution across the weld cross-section was obtained during double-pass FSW (DP-FSW). SEM and EDS analyses showed an increase in the fraction of second phase particles (SPPs) and the formation of new SPPs by DP-FSW. An increase in hardness values by 13.3% and a severe decrease in joint efficiency by 46.7% were observed by DP-FSW. Fractography examination of fractured surfaces of welded specimens showed a quasi-cleavage and ductile mode of failure in SP and DP joints, respectively. The potentiodynamic polarisation test of base metal and welded specimens indicated the high corrosion resistance of welded specimens.

Ex situ analysis of high-strength quenched and micro-alloyed steel during austenitising bending process: numerical simulation and experimental investigation

This paper compares the microstructure and mechanical evolution in a high-strength quenched and micro-alloyed steel during the austenitising bending process. Simulation results indicated a new finding that the stress neutral layer (SNL) tends to move to the tension zone during straining. The hardness gradient detected from the centre to compression/tension zones was resulted from comprehensive factors: First of all, the location of SNL revealed a prominent impact on strength. Second, the dislocation accumulation would be responsible for the hardness gradient on the surfaces. In addition, the overall strength decrease during straining was mainly ascribed to integrated effects of dynamic recovery (DRV) and dynamic recrystallisation (DRX). Apart from that, overall smaller martensite packet size and coarser prior austenite grains resulted in the increased hardness value at a lower bending degree. Also, the high consistency between experimental and simulation results is instructive for the practical forming process of railway spring fasteners.

Al2024/SiC Kompozitlerin Yüksek SiC Takviyesi ile Üretimi ve Karakterizasyonu

In this study, the production of Al2024/SiC particles containing 10%, 20% and 40% by weight SiC reinforcement by mechanical milling (MM) method and the compaction of these produced particles by hot pressing (SP) method were carried out. The effects of SiC particle reinforcement in varying weight ratios (%10, 20 and 40) in the structure on morphology, microstructure, elemental analysis, hardness and density properties were investigated. As a result of the experimental studies, a homogeneous elemental distribution was observed in the microstructure thanks to the homogeneous particles obtained by the MM process. However, it was determined that the amount of SiC particles increasing in weight in the structure caused the formation of porosity. The % relative density values of the composite samples with 10, 20 and 40 wt% SiC contents were measured as 99.060%, 98.301% and 95.252%, respectively. A very high increase in hardness values was observed with the increase in weight of SiC particle reinforcement in the structure. Hardness values were measured as 177.23 HV(0.5), 250.617 HV(0.5) and 316.67 HV(0.5) for Al2024/SiC composite materials containing 10, 20 and 40 wt% SiC particles, respectively.

Physical simulation on Joining of 700 MC steel: A HAZ and CCT curve study

In the present work, coarse grain heat-affected zone (CGHAZ) was simulated by Gleeble 3800 thermo-mechanical simulator. A continuous cooling transformation (CCT) diagram was generated from the results of the dilatometer, hardness, and microstructure analysis. The heating rate of 100 °C s−1, the peak temperature of 1300 °C, the holding time of one second, and thirteen different cooling conditions representing the actual welding condition were chosen here for simulation where the cooling rate was controlled by t8/3. At slow cooling rate ferrite, cementite, pearlite, and bainite were obtained. At a medium cooling rate, ferrite, bainite, and a small amount of martensite were observed. At a fast-cooling rate i.e., 100 °C s−1 fully martensite was obtained. The obtained hardness values were 225 HV, 263 HV, and 342 HV for slower, medium, and fast cooling rates respectively. The increase in hardness value shows that the amount of non-diffusional phases increases with an increase in cooling rate. The CCT curve shows the range of cooling rate and phase transformation temperature of ferrite, bainite, and martensite.

Pressure‐induced enhancement of mechanical performance in ZrC system

AbstractSuperhard materials are indispensable for use in cutting and polishing, as well as for nuclear reactor construction. As a candidate for hard material, ZrC has been extensively studied but not in its pressurized phase. Through evolutionary algorithm and density functional theory, we narrowed down the stoichiometry of Zr and C elements at various elevated pressures. The semimetal property of Zr4C4 continues to exist at high pressures but with lower electrical conductivity. Ionic and covalent bonding coexist around the pseudogap for high pressure phases. Both elastic constants and elastic moduli are found to increase steadily with surrounding pressure, connoting the superior mechanical and thermal characteristics of Zr4C4. This can be seen in the increased hardness values, higher melting temperatures, and better machinability indices for Zr4C4 as pressure rises. The predicted G/B and Poison's ratios have both agreed that Zr4C4 exhibits a transition from brittle to ductile behavior when the applied pressure goes above 85 GPa, displaying an overall improved mechanical performance.

Nutritional Improvement of Gluten-Free Breadsticks by Olive Cake Addition and Sourdough Fermentation: How Texture, Sensory, and Aromatic Profile Were Affected?

There is a growing need for gluten-free bakery products with an improved nutritional profile. Currently, gluten-free baked goods deliver low protein, fiber, and mineral content and elevated predicted glycaemic index (pGI). Olive cake (OC), a by-product from virgin olive oil extraction, is an excellent natural source of unsaturated fatty acids, dietary fiber and bioactive molecules, including polyphenols and tocopherols. In this framework, this study aimed at using two selected lactic acid bacteria and a yeast for increasing the antioxidant features and the phenol profile of the gluten-free breadsticks fortified with OC with the perspective of producing a functional food. Control (CTR) samples were prepared and compared with fermented ones (fCTR). Samples were added with either non-fermented OC (nfOC) or fermented for 12 and 20 h (fOC-12 and fOC-20). Our results showed that the predicted glycemic index (pGI) was influenced by both OC addition and sourdough fermentation. In fact, the lowest value of pGI was found in fOC-12, and hydrolysis index and pGI values of samples with OC (fOC-12 and nfOC) were statistically lower than fCTR. Both OC addition and fermentation improved the total phenol content and antioxidant activity of breadsticks. The most pronounced increase in hardness values was observed in the samples subjected to sourdough fermentation as evidenced both from texture profile analysis and sensory evaluation. Moreover, in most cases, the concentration of the detected volatile compounds was reduced by fermentation. Our work highlights the potential of OC to be upcycled in combination with fermentation to produce gluten-free breadsticks with improved nutritional profile, although additional trials are required to enhance textural and sensory profile.

First Principles Investigation of Binary Chromium Carbides Cr7C3, Cr3C2 and Cr23C6: Electronic Structures, Mechanical Properties and Thermodynamic Properties under Pressure

Binary chromium carbides display excellent wear resistance, extreme stiffness and oxidation resistance under high temperature. The influence of applied pressure on electronic structure, elastic behavior, Debye temperature and hardness of Cr7C3, Cr3C2 and Cr23C6 have been investigated by the density functional theory (DFT) method. The results reveal that lattice parameters and formation enthalpy display an inverse relationship with applied pressure, and Cr3C2 exhibited optimal structural stability. Moreover, Cr-C orbital hybridization tends to be stronger due to the decreased partial density of states (PDOS) of the Cr atom. The difference in electronic distribution of binary carbides has also been investigated, which confirmed that overall orbital hybridization and covalent characteristics has been enhanced. The theoretical hardness was elevated according to the higher bond strength and bond density. In accordance with structural stability data, Cr3C2 has shown maximum theoretical hardness. Furthermore, the anisotropic nature of hardness has been evaluated with external pressure. Cr3C2, and the highest isotropic hardness behavior along with an increase in hardness values with increasing pressure has been observed. In addition, the variation in Debye temperatures of binary chromium carbides under applied pressure has also been predicted. The results provide a theoretical insight into electronic, mechanical and thermodynamic behavior of three binary chromium carbides and show the potential of these novel carbides in a wide range of applications.

Nature of metal drop displacement during deposit welding elements of railway transport

The transformation of the microstructure of the heat-strengthened steel 65G section deposited with an electrode with a low-carbon rod is complex. Increased hardness values of individual areas contribute to an increase in the abrasive wear resistance of the part. The presence of a fusion zone ensures the resistance of the deposited area of an element on railway transport to cracking. The use of electrodes with a low-carbon rod is advisable when carrying out surfacing reinforcement of heat-hardened steels. The authors obtained mathematical expressions for the speed of displacement of a metal drop falling from the electrode material and the path it traverses when deposit welding elements on railway transport. They show that the displacement of this drop is accompanied by acceleration followed by deceleration. In electromagnetic deposit welding, the experimental assessment of the level of circumferential and radial residual thermal stresses during deposit welding of a coating on a hollow cylinder is of considerable practical interest. As an example, the calculation and experimental analysis of the stress state during deposit welding of the cylinder on the inner surface is made. He showed that residual compressive stresses, significant in magnitude, are formed on the outer surface. The method, which is limited to cutting the cylinder along the generatrix, without subsequent layer-by-layer removal of metal from its inner surface, is a simple and effective method for determining the circumferential residual stresses that provides the required accuracy.

Analisa Kekerasan dan Keausan Cylinder Sleeve dari Besi Cor Kelabu FC250 Hasil Sand Mold Casting

<p><em>The Cylinder sleeve is an engine component that is mounted on the cylinder block which functions as a piston glide base. The cylinder sleeve is made of FC250 gray cast iron. FC250 is a gray cast iron that has lamellar graphite with a tensile strength of at least 250 MPa. This study aims to determine the mechanical properties of hardness and wear of the Cylinder Sleeve made of gray cast iron FC250. The method used in this research is gray cast iron which is cut with a length of 5.5cm, thickness 0.7cm, height 0.7cm which is formed according to the standard size of the hardness and wear test. The tests carried out include testing brinell hardness and wear. The results showed that the lowest hardness value was 134.63BHN and the highest hardness value was 191.43BHN. The increase in hardness values is influenced by the carbon content that cannot be spread evenly, which is followed by a fast cooling rate. The results of the wear test obtained the lowest price of 0.00017mm³/kg.m and the highest wear price of 0.00028 mm³/kg.m.</em></p><p><em><br /></em></p>

Effect of Forging Deformation and Cooling on Mechanical Properties of Martensitic Stainless Steel

Stainless steel has good mechanical properties compared to other materials for strength and hardness, usually it will increase in hardness after hardening or forging. The purpose of this study was to obtain information about: The value of hardness and tensile strength of martensitic stainless steel forging with various deformations and cooling. The research method used is an experimental method, namely by forging on martensitic stainless steel with variations in deformation and cooling rate. Variations of forging deformation used are 25%, 50%, and 75%. The cooling media used are water, oil and air. The results of forgings with various cooling media were tested for tensile strength and tested for hardness using the Rockwell C (HRC) method. It was found that the higher the value of forging deformation, the higher the value of strength and hardness of martensitic stainless steel. This is because more and more martensite structures are recrystallized. In addition, it was also found that water and air cooling media gave an increase in the hardness of martensitic stainless steels. This is influenced by the cooling rate, where the higher the cooling rate, the more martensite structures formed, thus increasing the hardness value. The increase in hardness value is proportional to the increase in yield strength and tensile strength.

Novel investigation on tribological behavior of microwave synthesized functionally graded claddings

In this study, functional performance of Ni/Cr3C2 functionally graded claddings (FGCs) was investigated under dry sliding wear environment. The Ni/Cr3C2-based FGCs were produced by varying Cr3C2 fraction (Ni-XCr3C2) (X=10%–30% by weight) using microwave irradiation. The FGC layers were composed of cellular-structure with reinforced particles dispersed randomly inside Ni-based matrix. Variation of Cr3C2 particles inside Ni matrix exhibited significant impact on micro-structural and mechanical properties. The microhardness profile of the FGC layers showed an increase in hardness value with an increase in the amount of reinforced Cr3C2 particles. FGC top layers showed the maximum value of micro-hardness of 555 ± 34 HV. Functional performance of microwave processed FGCs was studied through the pin-on-disk tribometer under varying sliding velocity and sliding distances. For comprehension study, wear study was also carried out on microwave processed single layer clads with compositions corresponding to FGC layers. The FGC sample showed better wear resistance than all single clad layers and substrate material. The FGC sample exhibited 1.6 times less wear rate than the Ni-based + 30% Cr3C2 single layer clad. The worn-out surfaces of FGC and single-layer-clads showed presence of multiples cracks and grooves, which resulted in their weight loss during dry sliding contact. Material debonding and the formation of craters and cracks are the main phenomena responsible for the wear loss in the FGC surface.

Small percentage reinforcement of carbon nanotubes (CNTs) in epoxy(bisphenol-A) for enhanced mechanical performance

Epoxies, in its various forms, find wider applications in the field of automobile, aircrafts, marine and other structures. The recent development of carbon based nano particles like carbon nanotubes (CNTs), as reinforcement, has increased the scope to enhance mechanical properties of epoxy based composites. The present report is an attempt to understand the effects of very small percentage reinforcement of CNTs (i.e. 0.25 wt%) in epoxy on mechanical properties of nanocomposite. The solution mixing method was used to synthesize the nanocomposite. The CNTs were dispersed in a solvent using the probe sonicator. After complete dispersion of the CNTs, the epoxy was added under constant stirring condition. To cure the epoxy, amine based curing agent was used at room temperature for 24 h. Post curing was done for 2 h at 80 °C. The samples were prepared in aluminum moulds. Morphology of nanocomposite was studied with scanning electron microscopy (SEM). Mechanical properties of nanocomposites were characterized using nano indentation technique. Even at small reinforcement of 0.25%wt. of CNTs, epoxy-CNTs composite shown an 36% increase in Modulus and 16% percentage increase in hardness values compared to pristine epoxy composite. Present results supplemented the research data and reports favorable enhancement in mechanical properties even at small CNTs reinforcement.

Development of buffalo milk ice-cream by high pressure-homogenisation of mix: Physicochemical, textural and microstructural characterisation

This study aimed to determine the physicochemical, textural, and microstructural characteristics of buffalo milk ice cream produced from high-pressure homogenisation (HPH) treated ice cream mix. Ice cream mix was subjected to 0 (control), 30, 60, 90, 120, or 150 MPa. HPH increased the firmness and consistency value of mixes, whereas it decreased cohesiveness and index of viscosity values. Also, HPH improved the lightness, redness, and yellowness of the mix. The mean particle size of HPH-treated mix samples was lower than the control, except HPH-150. The hardness of ice cream samples was between 14.30 and 77.81 N, in which HPH increased hardness value with the increasing pressure. The overrun of ice cream samples ranged from 19.93 to 45.15%, and HPH decreased it. HPH significantly improved resistance to melting in the ice cream. Scanning electron microscopy images revealed that HPH reduced the size of air bubbles. HPH at 150 MPa resulted in a foamy structure in the ice cream. HPH can alter the hardness, microstructure, and melting characteristics of buffalo milk ice cream. Products with improved properties may be developed by further modifying the formulation and processing parameters.