Hardness Properties Research Articles

Effect of Wet Grinding Concrete Slurry Waste on Hydration and Hardening Properties of Cement: Micro-Nano-Scale Modification.

The concrete slurry waste (CSW) produced by concrete mixing plants is a type of hazardous waste that is difficult to handle. To better recycle the CSW separated from the aggregates, this study uses a variety of wet-grinding processes to refine the solid in it, replaces some of the cement with the solid particles in wet grinding concrete slurry waste (WCSW), and investigates the properties of WCSW and its effect on the hydration and hardening properties of cement. The results show that a suitable wet-grinding process can ensure that the particle size in WCSW is less than 10 μm, the particle morphology is more flat, and the degree of hydration is higher. The WCSW particles can promote early cement hydration; after adding WCSW, the heat release peak of cement hydration appears earlier and more early hydration products are produced, and with the increase in the substitution amount, the promoting effect on early cement hydration will be more significant. The WCSW particles have a great effect on improving the strength of mortar, especially in the early stage. At 1 d, when the substitution amount is 7.5 wt.%, the compressive and flexural strength is increased by 43.67% and 45.04%; this is related to the filling of matrix pores and the improvement of the interface transition zone by micro- and nanoparticles. After the wet grinding of CSW, fine WCSW particles are obtained, which can improve the performance of cement-based materials by replacing cement.

Studying mechanism of anisotropic crack generation on C-, R-, A-, and M-planes of sapphire during ultra-precision orthogonal cutting using a visualized slip/fracture activation model

With the growing demand for the fabrication of microminiaturized components, a comprehensive understanding of material removal behavior during ultra-precision cutting has become increasingly significant. Single-crystal sapphire stands out as a promising material for microelectronic components, ultra-precision lenses, and semiconductor structures owing to its exceptional characteristics, such as high hardness, chemical stability, and optical properties. This paper focuses on understanding the mechanism responsible for generating anisotropic crack morphologies along various cutting orientations on four crystal planes (C-, R-, A-, and M-planes) of sapphire during ultra-precision orthogonal cutting. By employing a scanning electric microscope to examine the machined surfaces, the crack morphologies can be categorized into three distinct types on the basis of their distinctive features: layered, sculptured, and lateral. To understand the mechanism determining crack morphology, visualized parameters related to the plastic deformation and cleavage fracture parameters are utilized. These parameters provide insight into both the likelihood and direction of plastic deformation and fracture system activations. Analysis of the results shows that the formation of crack morphology is predominantly influenced by the directionality of crystallographic fracture system activation and by the interplay between fracture and plastic deformation system activations.

Influence of Borides on microstructure and mechanical properties of a Ni alloy

Abstract Ni alloys are known to exhibit superior creep strength, chemical stability, and thermal resistance behavior at elevated temperatures. However, they also exhibit inadequate mechanical performance. Hence, the microstructures and, in relation to that, mechanical properties need to be improved. In this study, the effect of reinforcement of TiB2 on microstructural and mechanical properties was evaluated. The Ni matrix is reinforced with TiB2 particles. TiB2–Ni composites were successfully produced by the hot pressing method. Homogenously distributed TiB2 particles were observed in the microstructure using the energy dispersive spectrometry (EDS) mapping technique. The hardness of the reinforced samples was considerably improved by 2.65–8.12 times compared to pure Ni and between the different content of borides. A three-point bending test was performed to examine the mechanical behaviors of the reinforced composites. The bending stress properties of metal matrix composite (MMC) were significantly influenced by TiB2 content both positively and adversely. The optimum chemical content was determined based on bending tests and fractography. As a result, the 15 wt.% TiB2-reinforced sample exhibited superior microstructural (density), hardness, and bending properties compared to pure Ni and other reinforced samples with different ratios.

Friction, wear, and hardness properties of hybrid vehicle brake pads and effects on brake disc roughness

Abstract Considering the emerging importance of a sustainable green environment today, this study contributed to realizing resource sustainability by expanding the use of natural materials in the brake pad sector. Brake pads used in vehicle applications were developed using natural components, and their effects on brake performance properties were observed in brake pad samples containing four different amounts of natural components with additive rates of 0 %, 4 %, 8 %, and 12 %. Tests were conducted on the pad tester to determine the samples’ friction coefficient and wear rates. Hardness measurements were made with a Shore D measuring device. Average and maximum disc roughness were measured to determine the effect of brake pads on the brake disc. Microscopic analyses were performed with a scanning electron microscope. The results showed that using tamarind seed powder in the pad content created a synergy with alumina, brass powder, and graphite as friction modifiers, and the friction coefficient increased slightly. Considering the emerging importance of a sustainable green environment today, it has been determined that using natural materials contributes to realizing resource sustainability by expanding its application in the brake pad sector and positively affecting the brake system disc roughness.

Properties Enhancement of Metal Additive Manufactured Part via Cold Deformation Process

Wire-arc additive manufacturing is a method of 3D printing metal using welding techniques. However, due to heat, the mechanical properties of the deposited material may be affected. Various methods have been proposed to mechanically improve the properties. In this study, cold deformation was introduced to enhance the properties. The effects of a few parameters, including welding speed, wire feed rate, heat input, thickness ratio, and types of material, were studied. Based on the result, the hardness, tensile, and wear properties of the manufactured part improved, while other properties, like impact toughness, had a lower value. Based on the preliminary result, cold deformation shows potential alternatives for part repair or reconstruction of worn or broken parts.

Influence of Fe2O3 on synthesis, structure, hardness, and radiation shielding properties of Apatite–Wollastonite (AW) glass ceramics for bone implantation and shielding applications

This paper explores the important impact of Fe2O3 on the synthesis, structure, hardness, and radiation shielding characteristics of Apatite–Wollastonite (AW) glass ceramics for bone implantation and shielding application. The prepared studied samples were prepared and the effects of Fe2O3 addition on the synthesis process, density, and different physical and structural parameters comprehensively investigated. Additionally, the radiation shielding properties were determined by using PHITS simulation code and XCOM calculations for all samples. The results reveal that there is a significant impact of Fe2O3 addition on density, hardness, and radiation shielding of AW glass ceramics. The Vickers hardness values were calculated as 547, 598, and 621 Hv in measurements under 0.1 kg load., the density values are found to be as 2.87, 3.07 and 3.28 g/cm3 for AW, Aw -1Fe, and Aw -2Fe, respectively. The highest linear attenuation coefficient in the AW- 2Fe is 0.096 cm−1, Aw -1Fe showed 0.084 cm−1 and AW gave 0.072 cm−1 at 6 MeV. This study underscores the pivotal role of Fe2O3 as a multifaceted modifier in tailoring the properties of AW glass ceramics for bone implantation and other diverse applications extending from medical imaging to radiation and charged ions shielding.

High-temperature tribological properties of (TiZrNbMoTa)N and (TiZrNbMoTa)CN ceramic coatings

As dry-cutting tool coatings, high-entropy ceramics (HECs) exhibit excellent hardness, toughness, and wear resistance properties. However, the hardening mechanism of HEC coatings and their mechanical and frictional properties under high-temperature conditions have not been studied. In this study, we successfully prepared (TiZrNbMoTa)N high-entropy nitride (HEN) and (TiZrNbMoTa)CN high-entropy carbon nitride (HECN) coatings using reactive magnetron sputtering technology. The strengthening mechanism and thermodynamic properties of HEN and HECN coatings were systematically studied using the Debye-Grüneisen quasi-harmonic approximation model combined with density functional theory (DFT) calculations. At room temperature (RT, 25 °C) and high temperature (HT, 500 °C), the microhardness of HECN is 62 % and 56 % higher than that of HEN, respectively. Especially at RT, the microhardness of HECN reaches 46.37 GPa. Through in-situ XRD, in-situ nanoindentation, and high-temperature friction and wear analysis, we conducted in-depth research on the phase stability, high-temperature mechanical properties, and high-temperature tribological properties of HECs coatings in high-temperature. XRD test results show that HEN and HECN coatings exhibit a single-phase FCC structure and maintain good stability under HT. DFT calculation results show that the M − C bond in HECN is stronger than the M − N bond in HEN, which is why the HECN coating is harder. At HT, the wear rate of HECN coating is only reduced by 10 % compared with HEN coating. Different from RT, under high-temperature conditions, the primary wear mechanism of the coating is oxidative wear. The coating's red hardness and friction coefficient (COF) have a limited impact on the coating's high-temperature anti-wear performance. This research provides a theory and technical basis for designing and preparing protective coatings with high hardness and low friction coefficient.

Development and Characterization of Hybrid Particulate-fiber Reinforced Epoxy Composites

Although considered wastes, animal fibers and gastropod shell particles are biodegradable, have low density, high stiffness, considerably high impact absorption capacity and relatively low cost. Therefore, they are finding increasing use as reinforcement materials in polymer composites. This research work studied the tensile, hardness, and wear resistance properties of hybrid snail shell (SSP) and chicken feather barb fibers (CFB) reinforced epoxy composites. The stir cast molding technique was utilized to synthesize the composite samples with 3, 6, 9, 12, 15, and 18 wt.% of the hybrid SSPs/CFB. Compared with the control samples, SSP/CFB hybrid reinforcements enhanced the mechanical properties of the composites. Composites with intermediate weight fraction of 9 wt.% SSP/CFB exhibited overall optimum properties when benchmarked against the control sample with approximately 37, 37, 133, 19, and 59% improvement in wear, hardness, impact, and ultimate tensile strength properties respectively. These enhancements suggested a synergistic effect of the two reinforcement phases. The results presented in this study demonstrated the potential of utilizing bio-derived waste materials for synthesizing eco-friendly composites.

Silica nanoparticle-reinforced polyurethane plastic immobilized with strontium aluminate nanofiller: Ultraviolet protection, superhydrophobicity and photoluminescence

A simple strategy was reported toward a possible industrial preparation of smart plastic materials with persistent afterglow, ultraviolet protection, superhydrophobic properties and photochromism. Nanoparticles of rare-earth doped aluminate (NREA) were embedded into a polyurethane plastic composite. A combination of polyurethane (bulk material), silica nanoparticles (nanofiller), and NREA (luminous agent) was prepared. Achieving a uniform distribution of NREA in a polyurethane fluid allows for the manufactured plastic to be colorless. NREA showed diameters between 12 nm and 26 nm. When excited at 365 nm, the produced photoluminescent polyurethane composite demonstrated an emission band at 519 nm. NREA contents more than 1 % were found to exhibit persistent photoluminescence, whereas pigment concentrations less than 1 % were found to exhibit fluorescence emission. The created plastic concrete exhibited photochromism, as shown by the coloration parameters and photoluminescence spectra, which proved a change in color between transparent during daylight, green under ultraviolet rays, and greenish-yellow in darkness. The static contact angle tests demonstrated effective superhydrophobic properties. Significant improvements were detected ultraviolet protection and photostability. The hardness properties, structural compositions, and morphology of the developed polyurethane plastics were also explored.

Enhancement of hardness and tribological properties of AISI 321 by cathodic cage plasma nitriding at various pulsed duty cycle

AISI 321, an austenitic stainless steel, has high corrosion and temperature resistance, making it useful for aerospace and chemical processing. Cathodic cage plasma nitriding (CCPN) is a versatile technique that enhances material surface characteristics. This study aims to investigate the effect of the pulsed duty cycle from 10 % to 60 % on microhardness and tribological properties through CCPN treatment. The X-ray diffraction (XRD) analysis indicates a noticeable shift in the γ-phase towards the lower 2θ angle originating from the expanded austenite phase γN by the lattice expansion at the lowest duty cycle. Nitriding at the lowest duty cycle reduced the average crystallite size from 68 nm (untreated) to 4.5 nm, while increasing the duty cycle led to a decrease in micro-strain. The surface microhardness of the sample that underwent the lowest duty cycle improved to 1288 HV0.01 compared to the untreated sample (210 HV0.01). Moreover, the lowest wear rate is observed for the sample nitrided at a low-duty cycle, which agrees with hardness and strain behavior. The results show that the variable pulsed duty in CCPN can improve the surface hardness and tribological properties of AISI 321, particularly at low-duty cycles.

Effect of hybrid ratio and sintering temperature on hardness properties of hybrid AMCs

The present research work is aimed toward fabrication of hybrid Aluminium matrix composites (AMCs) of different hybrid ratios of Alumina (Al2O3) and Silicon Carbide (SiC) followed by investigation of their microstructure and hardness properties. Hybrid AMCs were fabricated through powder metallurgy process by adding 5 wt% and 10 wt% mixture of Al2O3 and SiC reinforcements of various hybrid ratios (0:1, 1:3, 1:2, 1:1, 3:1, 2:1 and 1:0) with the pure Aluminium powder. The mixture powder were properly mixed by ball milling arrangements for 6 h. The mixture powder were preheated at 500 °C for 2 h in a high temperature programmable tube furnace followed by immediate compaction under a closed die at 1500 psi pressure through automatic hydraulic press. The compacted specimens were then sintered at 350 °C, 500 °C and 650 °C for 2 h in the same furnace. Hardness test of the fabricated hybrid AMCs were carried out by Vickers Micro-hardness testers and hardness values were measured by the integrated software. The hardness properties of hybrid AMCs also were compared with the hardness properties of pure Aluminium specimens fabricated through the same process route and process parameters. It is interestingly observed that hardness of hybrid AMC is more when pure Aluminium powder is reinforced with only SiC of same wt.% for both the cases (5 wt% and 10 wt% reinforce AMCs) and it decreases with decrease of weight fraction of SiC and simultaneously increase of weight fraction of Al2O3 keeping total weight fraction of mixture as constant.

Response surface methodology and machine learning optimisations comparisons of recycled AA6061-B4C–ZrO2 hybrid metal matrix composites via hot forging forming process

The optimal conditions of applied factors to reuse Aluminium AA6061 scraps are (450, 500, and 550) ⁰C preheating temperature, (1–15) % Boron Carbide (B4C), and Zirconium (ZrO2) hybrid reinforced particles at 120 min forging time via Hot Forging (HF) process. The response surface methodology (RSM) and machine learning (ML) were established for the optimisations and comparisons towards materials strength structure. The Ultimate Tensile Strength (UTS) strength and Microhardness (MH) were significantly increased by increasing the processed temperature and reinforced particles because of the material dispersion strengthening. The high melting point of particles caused impedance movements of aluminium ceramics dislocations which need higher plastic deformation force and hence increased the material's mechanical and physical properties. But, beyond Al/10 % B4C + 10 % ZrO2 the strength and hardness were decreased due to more particle agglomeration distribution. The optimisation tools of both RSM and ML show high agreement between the reported results of applied parameters towards the materials' strength characterisation. The microstructure analysis of Field Emission Scanning Electron Microscopy (FE-SEM) and Atomic Force Microscope (AFM) provides insights mapping behavioural characterisation supports related to strength and hardness properties. The distribution of different volumes of ceramic particle proportion was highlighted. The environmental impacts were also analysed by employing a life cycle assessment (LCA) to identify energy savings because of its fewer processing steps and produce excellent hybrid materials properties.

SAE 1006

Abstract 1006 is a wrought low-carbon (carbon ≤ 0.08%) non-alloy steel that is used in the as rolled, annealed, normalized, or cold worked condition. This steel is characterized by low strength, high ductility, excellent cold formability, and excellent weldability. Within the carbon range of this steel grade, both strength and hardness will increase with increase in carbon and with cold work. Such increases in strength are at the sacrifice of ductility or the ability to withstand cold deformation. 1006 is widely used for lightly stressed parts where cold formability or drawability is the primary requisite. In general, it is not intended for heat treatment after cold working. 1006 may, however, be used in the case hardened, nitrided, or nitrocarburized condition. This datasheet provides information on composition, physical properties, microstructure, hardness, and tensile properties. It also includes information on forming and heat treating. Filing Code: CS-267. Producer or source: Heat Treater's Guide.

ACO EUROBAR EN-GJS-400-18C-LT (5.3123)

Abstract ACO Eurobar EN-GJS-400-18C-LT is a ferritic spheroidal graphite cast iron that is produced by the continuous casting process. It has a minimum tensile strength of 400 MPa (58 ksi) and a minimum elongation of 18%. It has a tensile strength exceeding that of the highest-tensile-strength grade of gray cast iron, together with much higher elongation and impact resistance. It is specifically designed to provide good impact properties at low temperature. This datasheet provides information on physical properties, hardness, elasticity, and tensile properties as well as fracture toughness and fatigue. It also includes information on low temperature performance as well as casting, heat treating, and machining. Filing Code: CI-109. Producer or source: ACO Eurobar GmbH.

Influence of Mulberry Leaf Powder Additive on Chemical and Physical Characteristics of Wheat and Rice Flour Butter Cookies.

People of all age groups consume cookies every day. Consumers' preferences for cookies supplemented with functional plant raw materials have recently increased. Therefore, this research aimed to investigate the influence of a mulberry leaf additive on the proximate and mineral compositions, total phenolic and total chlorophyll content, antioxidant activity, and the hardness and color properties of butter cookies. Wheat and rice flour butter cookies were prepared by replacing the flour with mulberry leaf powder at 0, 4, 8, and 12% (w/w). The results revealed that the investigated chemical and physical characteristics of butter cookies depend on the flour used (rice or wheat) and the addition of mulberry leaf powder. Wheat and rice flour cookies with 12% mulberry leaf powder had the significantly highest contents of fiber (20.34 and 20.23%, respectively), ash (1.73 and 1.75%, respectively), K (170.22 and 160.22 mg 100 g-1, respectively), and Ca (170.45 and 160.68 mg 100 g-1, respectively). The rice flour cookies enriched with 12% leaf powder had the greatest amounts of total phenolics (1.48 mg 100 g-1), Zn (12.25 mg kg-1), Mn (6.28 mg kg-1), Cu (1.95 mg kg-1), and antioxidant activity (67.98%). However, the wheat cookies without mulberry leaf powder contained the most B (9.12 mg kg-1), while the no-added rice cookies contained the most Fe (14.30 mg kg-1). Replacing flour with leaf powder increased the cookies' hardness and decreased their lightness. In conclusion, enriching butter cookies with freeze-dried mulberry leaves can improve their nutritional value and antioxidant activity.

Effect of solution and artificial aging heat treatment on the hardness, friction and wear properties of laser cladding and roll-formed 18Ni300 materials

Abstract 18Ni300 is widely used in precision moulds, national defence, and other engineering fields due to its high strength and toughness, and because its properties can be greatly changed after heat treatment. In this research, the 18Ni300 cladding layer was fabricated on 18Ni300 substrate using the laser cladding method and a solid solution artificial aging treatment was carried out to analyse its macro morphology and metallographic organization. Comparison of hardness, friction, and wear of cladding layers manufactured by laser cladding and of materials produced by rolling was performed before and after heat treatment. The results show that the solution and artificial aging heat treatment has a significant effect on the microstructure of the cladding layer fabricated by laser cladding. There are obvious differences in the organization and morphology of different parts of the cladding layer before heat treatment; the metallographic organization and morphology of different parts of the cladding layer after heat treatment are the same. The trend of change of material hardness before and after heat treatment is the same in that the cladding layer is greater than the rolled material and the hardness of the material after heat treatment is much greater than the hardness of the material before heat treatment. The hardness and wear resistance of the material after solution and artificial aging heat treatment has been significantly improved, and the impact on the rolled production material of the melted cladding layer manufactured by laser cladding is even greater.

Designing innovative PAni-based adsorbents for CO2 capture via in-situ nitrogen plasma modification for sustainable development

Carbon dioxide (CO2) capture is a critical strategy in the fight against climate change. By implementing this innovative technology, CO2 emissions from diverse sources will be captured and neutralized, thereby mitigating global warming. For this purpose, novel sorbents were developed in this work by loading TiO2 and ZnO nanofillers into a polyaniline (PAni) system to form PAni–TiO2 (PT) and PAni–ZnO (PZ) composites. Following that, in-situ nitrogen (N2) plasma treatments were applied for 5 min to improve their surface nature and physiochemical properties. The CO2 capture qualities of modified PT and PZ sorbents were investigated, as well as physical assessments of their microstructure, nuclear magnetic resonance (NMR), morphology, contact angle, roughness, electrical optical, reactivity, stability, and adsorption capability, hardness, softness and electrophilicity properties. Bombardment of high-energy plasma species for 5 min was sufficient to optimize the crystallite size and crystallinity degree in both the PT5 and PZ5 systems. These enhancements may be related to the growth of protonated benzoid rings -NH+- as a result of plasma modifications to the structure of PAni and its transformation into emerald salt. In a similar vein, the SEM micrographs, porous topography and hydrophilic nature of the PAni composites varied with respect to the type of nanofillers and plasma level. The plasma treatment provided additional oxygen-containing functional groups as active sites for chemical interactions, including CO2 via chemisorption or physisorption, facilitating further reduction. Additionally, plasma activities assisted in shifting to a rougher surface (i.e.,Ra = 3.83 µm) as well as optimizing the energy band gap (1.57 eV), which can accommodate more CO2 molecules, thereby improving the capture efficiency. Moreover, the findings indicate that PZ5 is more desirable for CO2 adsorption since it possesses a 2.52-fold greater CO2 adsorption energy (-0.079 a.u) than pristine PZ0. In the future, our work opens up exciting new prospects to achieve desired performance from CO2 capturing compounds utilizing plasma technology.

Assessment of microbial properties, and heavy metals contents of surface water and ground water samples In Ureje and Ireje, Ekiti State, Nigeria.

Water is everywhere, · it is the most basic and necessary element of life, as well as the most important and abundant compound in the ecosystem. Standard methods were used to evaluate the physicochemical properties, microbial properties, and heavy metal content of river and well water samples in Ekiti State, South-West Nigeria. Important parameter like pH, electrical conductivity, total dissolved solids, DO, BOD, turbidity, total alkalinity, total hardness, heavy metals and microbial properties are determined. The research work indicated that temperature, odour, pH, alkalinity, TDS, biochemical oxygen demand, DO, chloride, nitrate and turbidity were within the range of WHO permissible limits for drinking water while color, Conductivity, iron and manganese were above the WHO permissible limits. The study also indicated that the microbial contents such as total viable count, yeast/mold and coliform were above the WHO permissible limits for drinking. These results show that the water sources were slightly contaminated and unsafe for human consumption. This water must be treated before it may be consumed or used for domestic application.

Numerical and experimental study on effect of induction heating parameters on the coating of Zn layer on mild steel

The objective of the study is to determine the most effective induction heating parameters for melting pure zinc selectively over the mild steel substrate surface. The numerical simulation on effect of induction heating parameters on the mild steel substrate is studied using COMSOL Multiphysics 5.6 software. The optimised effective parameters are used for the experimental analysis for the validation. Variables such as coil configuration, stand-off distance (SOD), coil current and frequency were systematically changed, and optimal settings were chosen on the basis of time temperature contour curve and the heating rate within the material. Results of the numerical analysis portrayed that a pancake coil geometrical configuration, SOD of 2 mm, coil current of 300 A and alternating frequency of 300 kHz were found as the optimum set of parameters for the effective surface repair. An experimental investigation was carried out by depositing a thin layer of zinc on mild steel substrate using the optimized parameters. The surface integrity of the coated specimen was examined through the high-resolution optical microscopy, X-ray diffraction and electron back scattered diffraction (EBSD) techniques. The hardness property of the coated specimen was examined with a Vickers microhardness tester. The microstructure analysis and hardness measurement showed that consistent coating is achieved without affecting the base metal/substrate properties. The experimental results very much coincide with the numerical simulation.

Rapid preparation of nanocrystalline high-entropy alloy coating with extremely low dilution rate and excellent corrosion resistance via ultra-high-speed laser cladding

Ultra-high-speed laser cladding (UHSLC) not only offers an efficient solution to the limitations of conventional laser cladding but also aligns with the contemporary objectives of material conservation and efficiency enhancement in metal protective coatings. This study investigates the fabrication of CrFeCoNiMo0.2 high-entropy alloy (HEA) coatings using UHSLC and traditional laser cladding (TLC) methods. Key aspects such as macroscopic forming quality, element distribution, dilution rate, grain morphology, hardness, and electrochemical corrosion properties of both UHSLC and TLC coatings are thoroughly examined. Notably, UHSLC-produced coatings, with their significantly reduced thickness ranging from 100 to 300 μm, demonstrate an impressively low substrate dilution rate compared to the 2–3 mm thickness of TLC coatings. The rapid solidification inherent in UHSLC leads to smaller grain sizes in the coating, resulting in enhanced hardness. Moreover, the UHSLC coating exhibits superior corrosion resistance, characterized by a lower maintaining-passivity current density in 1 mol/L H2SO4 and a higher self-corrosion potential relative to TLC coatings. This work presents a novel approach, employing high-efficiency and low-cost laser-cladding technology, to minimize dilution in the matrix and improve the coating properties of HEAs.