High Level Of Hardness Research Articles

A multivariate statistical approach for monitoring of groundwater quality: a case study of Beri block, Haryana, India.

The present research deals with assessment of groundwater quality of Beri block, Jhajjar district, Haryana,India and its nearby villages. Multivariate statistics is an efficient technique to display relationship between different limiting factors. Around 24 groundwater samples were collected. A total of 16 variables were analysed: pH, potassium, total dissolved solids (TDS), hardness (calcium, magnesium and total), sulphate, sodium, electrical conductivity and phosphate, chloride (Cl-) and heavy metals, namely iron, chromium, lead and zinc. Principal component analysis is one of the commonly used tools in water quality assessment because it effectively reduces number of variables. Multivariate statistical tools "principal component analysis (PCA)" and "cluster analysis" were used to set up relationship among the studied parameters. PCA showed the existence of up to five significant PCs which account for 80.35% of the variance. Few parameters such as pH, sodium, potassium, sulphate, phosphate and zinc were found to be well within limits as approved by WHO and BIS, whereas parameters such as chloride, alkalinity, hardness, total dissolved solids and metals (Pb, Cr and Fe) were found to go beyond the prescribed limits. High levels of hardness, total dissolved solids and chlorides are responsible for saline behaviour of water. The correlation matrices for 16 parameters were executed. EC, TDS, chloride and total hardness were significantly and positively correlated with each other. pH and phosphate (PO42-) were negatively correlated with majority of the physicochemical variables. After studying the physiochemical properties of groundwater samples, it is recommended that water quality parameters should be analysed periodically to conserve the water resources and emphasis should be laid on water quality management practices.

Microstructural modification of a static and dynamically solidified high chromium white cast iron alloyed with vanadium

The objective of this study is to analyze the effect of dynamic solidification and vanadium additions in a range from zero to 6.42 ​wt% to a high chromium white iron with the purpose of refining the microstructure and to improve hardness. The alloys were characterized by optical and electron microscopy, EDS and X-ray diffraction and complemented with phase quantification undertaken by image analysis and XRD data. Bulk hardness was measured for different casting thicknesses in both as-cast and after a destabilization heat treatment at 900 ​°C for 45 ​min. The results show that V addition produces a refining effect on the M7C3 carbide as well as the VC carbide formation which can nucleate as primary carbide for V contents higher than 4.75 ​wt%. Dynamic solidification of the experimental irons produced a notable decrease in the size of the carbide phase and increased its volume fraction. This solidification technique also produced a transformation of the iron matrix of the base alloy from predominantly austenitic to a fully pearlitic matrix, while for the 6.42 ​wt% V alloyed iron a notably smaller, slightly elongated and isolated VC carbides embedded in a highly martensitic matrix were observed. This microstructural modification resulted in the maximum harness values obtained in the as-cast conditions. After the destabilization heat treatment, a softening of the microstructure of the V alloyed irons was observed due to the C depletion of the matrix inhibiting the martensitic transformation; conversely, the base alloy experienced a considerably increase in hardness as a result of the high amount of precipitated carbides embedded in a highly martensitic matrix. The results of the present study show that, V alloying and the dynamic solidification technique can be used as effective ways to refine the carbide phase obtaining high hardness levels in the as-cast condition, avoiding this way heat treatments.

Correlation Between the Indentation Properties and Microstructure of Dissimilar Capacitor Discharge Welded WC-Co/High-Speed Steel Joints.

The welding of cemented carbide to tool steel is a challenging task, of scientific and industrial relevance, as it combines the high level of hardness of cemented carbide with the high level of fracture toughness of steel, while reducing the shaping cost and extending the application versatility, as its tribological, toughness, thermal and chemical properties can be optimally harmonised. The already existing joining technologies often impart either insufficient toughness or poor high-temperature strength to a joint to withstand the ever-increasing severe service condition demands. In this paper, a novel capacitor discharge welding (CDW) process is investigated for the case of a butt-joint between a tungsten carbide-cobalt (WC-Co) composite rod and an AISI M35 high-speed steel (HSS) rod. The latter was shaped with a conical-ended projection to promote a high current concentration and heat at the welding zone. CDW functions by combining a direct current (DC) electric current pulse and external uniaxial pressure after a preloading step, in which only uniaxial pressure is applied. The relatively high heating and cooling rates promote a thin layer of a characteristic ultrafine microstructure that combines high strength and toughness. Morphological analysis showed that the CDW process: (a) forms a sound and net shaped joint, (b) preserves the sub-micrometric grain structure of the original WC-Co composite base materials, via a transitional layer, (c) refines the microstructure of the original martensite of the HSS base material, and (d) results in an improved corrosion resistance across a 1-mm thick layer near the weld interface on the steel side. A nano-indentation test survey determined: (e) no hardness deterioration on the HSS side of the weld zone, although (f) a slight decrease in hardness was observed across the transitional layer on the composite side. Furthermore, (g) an indication of toughness of the joint was perceived as the size of the crack induced by processing the residual stress after sample preparation was unaltered.

Utilization of Bio-sand Filter Technology to Reduce The Hardness of Groundwater in Bangunjiwo Village, Yogyakarta

Water is the most critical requirement for the community for daily needs. Groundwater in Bangunjiwo Village, Yogyakarta has a high level of hardness. groundwater in the village contains high Magnesium (Mg2+) and Calcium (Ca2+) reaches more than 180 ppm. The purpose of this study is to reduce the level of hardness of water in Bagunjiwo Village using bio-sand-filter technology. The sampling of groundwater in Bangunjiwo Village is done randomly at several different points. Water filtration with bio-sand-filter technology uses sand media by growing biofilm layers. Biofilm layers made from layers include gravel with a diameter of 2 cm, small gravel with a diameter of 1 cm, zeolites with a diameter of 0.5 cm, and layers of clay. Each layer is bordered by gauze. The arrangement is soaked in water for 21 days, resulting in biofilms in the media. The results of screening with bio-sand-filter technology showed a decrease in hardness of groundwater reached 78.67 % with a discharge of 0.5 litres per minute. Bio-sand-filters can absorb the content of Magnesium and Calcium even pathogens in the water. Bio-sand-filter technology is expected to be able to overcome community problems in Bangunjiwo Village, Yogyakarta.

Effects of Co2 and Nd:YAG Laser Remelting of the Ti6Al4V Alloy on the Surface Quality and Residual Stresses

Abstract The titanium alloys are materials susceptible to tribological wear and the laser treatment can be applied in surface treatment processes to obtain for example higher hardness level. From the other side, it is important to take into consideration, that hardness increase that can be connected with cracks. The aim of this research was to investigate the effects of different lasers and the process parameters on the form and level of residual stresses in the Ti6Al4V alloy, which determine the initiation and propagation of cracking. Two lasers were used, the CO2 and Nd:YAG lasers. The specimens were remelted in liquid nitrogen, water or calm air at different pre-heating temperature. The different laser power and scan rates were applied. The increase in energy density increased the number of cracks, the change of an environment and pre-heating affected alo the surface cracking. The cracks observed after remelting with Nd:YAG laser were longer than those observed after treatment with CO2 laser. The compressive stresses after the CO2 laser treatment, and tensile stresses after treatment with the Nd:YAG laser, were found. The appearance of cracks was attributed to an excessive energy density. The different distribution of heat energy inside and around the laser tracks was discussed as the origin of presence either tensile or compressive stresses in the alloy treated with different lasers.

Working Load Characteristics of the PDC-Cone Composite Bit under Impact and Scraping

The PDC-roller hybrid bit combines the cutting structure of a tricone bit with a PDC bit. It can achieve good results, breaking rock in directional drilling, drilling in inhomogeneous formations, and drilling in formations with high levels of hardness, and it can achieve the engineering goals of increasing speed and efficiency. First, we analyzed the rock-breaking mechanism of the composite bit and the principles of cushioning, torsion reduction, and prebreaking of the cone teeth during the breaking of rock. Second, cutting load models of the cone teeth and PDC teeth were established through unit experiments and through the calculation methods of the axial force, lateral force and torque, and lateral bending moment of the composite bit. Third, the digital simulation and analysis system was improved to include the function of calculating the working load of the composite bit. Taking an 8-1/2 inch, 2 + 4 type composite bit as an example, the working load characteristics of three cutting structures (cone, blade, and composite) were analyzed and compared. The analysis shows that the composite bit has high drilling efficiency, obvious deviation advantages, and good working stability under specific formation conditions. This paper provides technical support for the performance analysis, formation adaptability evaluation, and cutting structure design optimization of the PDC-cone bit.

Physical Characteristics of Probiotic Effervescent Tablets with Various Concentration of Maltodextrin as Coating Materials

The application of RICA (Research Institute for Coastal Aquaculture) liquid probiotic bacteria proved to be able to prevent attacks of both types of vibriosis disease and White Spot Syndrome Virus (WSSV) through improved pond water quality. This RICA liquid probiotics is coated using maltodextrin with 3 variations of concentration which are then formed into probiotic effervescent tablets. Apart from making it easy to distribute, this solid probiotic is easily applied without fermentation such as the use of liquid probiotics. The aims of this study was to determine the physical characteristics of probiotic effervescent tablets from maltodextrin coatings with different concentration. The concentration maltodextrin as coating materials were is 20%, 30% and 40% (b/v). The parameters test are average weight, friability, hardness and disintegration time. The results showed that the effervescent tablets of probiotics with a concentration of maltodextrin 40% had a mean weight higher than other concentrations at 798.88 mg. While the effervescent tablets of probiotic with a maltodextrin concentration of 20% had a lower friability and disintegration time compared to other concentrations of 0.05% and 12.96 minutes. And has a higher level of hardness that is equal to 10.89 N compared to other concentrations that is 30% and 40% concentration maltodextrin. The concentration of 20% maltodextrin was the best treatment of this study.

ВИЗНАЧЕННЯ ГРАНИЧНО ДОПУСТИМИХ ШВИДКОСТЕЙ ОХОЛОДЖЕННЯ ОБОДУ ЗАЛІЗНИЧНИХ КОЛІС ДЛЯ ФОРМУВАННЯ ОДНОРІДНОЇ СТРУКТУРИ

Compliance with the new more stringent requirements for railway wheels is possible only with an integrated approach to improving their production technology with a reasonable choice of heat treatment modes, taking into account the chemical composition of steel. The purpose of the study is the experimental and analytical determination of the maximum permissible cooling rate of the rolling surface and the minimum required cooling rate of the central sections of the rim of a railway wheel to achieve a high level of hardness of the ferrite-pearlite structure. The studies were carried out on steels of grades ER8 and ER7 according to EN 13262, grade 2 according to GOST 10791: 2016, steel of class C according to AAR M-107 / M-208. Based on the hardenability test (GOST 5657) by the end hardening method (according to the Jomeni method), the distance from the surface from which one-sided cooling was performed, where the hardness met the requirements of the normative documentation for wheels made of the steel under study, the distance where the formation of needle-like structures did not occur, was determined, including bainite and widmanstatt according to the results of metallographic studies and determination of hardness. Based on the results of temperature changes during the cooling process, the cooling rates were determined in places that met the specified conditions. In the work, modeling was applied in the QForm VX 8.2 software package, as a result, a model was developed for the adaptation of which the results of the experiment were used. The high convergence of the results of calculation and experiment was confirmed. At the same time, the model made it possible to obtain the instantaneous cooling rate in a form that is more consistent with the physical meaning of the process and to avoid the scatter of actual values associated with the discreteness of data recording. It was found that the instantaneous cooling rate changes during the continuous uniform supply of the coolant. In some cases, a significant slowdown in cooling was recorded, or even negative values of the instantaneous cooling rate. This is due to the release of the heat of phase transformation, which occurs during the decomposition of austenite by the diffusion mechanism. The developed model can be used to construct thermokinetic diagrams during continuous cooling and to develop recommendations for heat treatment modes to achieve the specified mechanical properties at a certain structural state.

The Effect of Zr on LM6 Aluminum Alloy

In this study, the effect of Zr amount on LM6 alloys which were produced by conventional casting method and contained different amounts of Zr (0.05% and 0.15) on the microstructure and mechanical properties of the alloys was investigated. In addition, produced alloys were modified with 200-250 ppm Strontium (Sr). optic microscope (OM) and scanning electron microscopy (SEM / EDS analysis) were used for microstructure analysis. The hardness and tensile tests of the alloys which were modified by Sr and alloyed with different amounts of zirconium were performed. As a result of the studies that were done, it was determined in the images of optical microscope (OM) and scanning electron microscope (SEM) that the morphology of Al-Si-Fe phase changed depending on the addition of Zr, and that Al-Si-Fe intermetalics having different amounts of Zr composed. While the highest level of percent elongation was obtained from the Al12Si alloy, the highest level of hardness and maximum tensile strength were obtained from the LM6 alloy modified by strontium. The highest level of yield strength was obtained from LM6 alloy which was alloyed with 0.05 Zr. It was found that the amount of added Zr did not show a significant difference at the maximum tensile strength level of Al12Si alloy.

Cold Sprayed Tungsten Armor for Tokamak First Wall

Harnessing nuclear fusion is a challenging task, in particular because of the demands put on the used materials. In tokamaks, future energy sources, the inner-most chambers are to be coated with dense coatings of W, or W-Cr-based alloys. So far, the attempts for such coatings formation by other methods failed due to oxidation, high porosity, insufficient adhesion, high specific surface, or even insufficient thickness below 10 μ m. Cold spraying seems a promising technology for the task. In our study, we demonstrate the first successful fabrication of thick pure W coatings. W-Cr and W-Cr-Ti coatings were further prepared without oxidation of the metals. All coatings exhibited high hardness levels, good interface quality with three tested substrates and, importantly, a promising potential for formation of stable Cr 2 WO x phases.

Assessment of water-quality parameters of groundwater contaminated by fly ash leachate near Koradi Thermal Power Plant, Nagpur.

Thermal power generating industries affect the surrounding environment in various ways. Fly ash escapes along with flue gases and can be found in undesirable quantities in soil and water sources in the region. The water quality of an area must be evaluated regularly to ensure the quality of potable water. The present study evaluates the pre-monsoon and post-monsoon concentrations of several important physico-chemical parameters and heavy-metal contents of groundwater samples collected from sites near the Koradi Thermal Power Plant, a major source of power generation in the Nagpur Region. The maximum amount of total dissolved solids observed during the two seasons studied were 1571mg/l and 1591mg/l which is within the desirable limit implying that fly ash contamination did not affect this water quality parameter. The total hardness of samples from GW-3, GW-5 and GW-9 were 844mg/l, 775mg/l and 675mg/l during pre-monsoon season, while GW-3 and GW-5 along with GW-4 continued to show high levels of total hardness at 1015mg/l, 741mg/l and 650mg/l, respectively. These values are higher than the permissible limit due to the high levels of ions of bicarbonate, calcium, sodium and sulphate derived from fly ash leachate. Statistical analysis showed that sulphides, total hardness, electrical conductivity and total dissolved solids were the significant water quality parameters of the region. The evaluation of the parameters found that the three water sources (GW-3, GW-5 and GW-9) out of 10 are the most affected groundwater sources of fly ash pollution.

Technological Aspects of Obtaining Functional Gradient Coatings to Protect Machinery from Wear

The article presents the results of research on the development of technology for the production of functional-gradient coatings with high levels of adhesive strength and hardness, as well as with low porosity. The coating was successfully tested and recommended to protect the elements and components of precision engineering.

Effect of Bias Voltage on Mechanical Properties of HiPIMS/RFMS Cosputtered Zr-Si-N Films.

Zr–Si–N films with atomic ratios of N/(Zr + Si) of 0.54–0.82 were fabricated through high-power impulse magnetron sputtering (HiPIMS)–radio-frequency magnetron sputtering (RFMS) cosputtering by applying an average HiPIMS power of 300 W on the Zr target, various RF power levels on the Si target, and negative bias voltage levels of 0–150 V connected to the substrate holder. Applying a negative bias voltage on substrates enhanced the ion bombardment effect, which affected the chemical compositions, mechanical properties, and residual stress of the Zr–Si–N films. The results indicated that Zr–Si–N films with Si content ranging from 1.4 to 6.3 atom % exhibited a high hardness level of 33.2–34.6 GPa accompanied with a compressive stress of 4.3–6.4 GPa, an H/E* level of 0.080–0.107, an H3/E*2 level of 0.21–0.39 GPa, and an elastic recovery of 62–72%.

Effects of glycerin application on the hardness of nanofilled composite immersed in tamarind soft drinks

Background: Loss of tooth structure is a consideration in the performance of restorative treatment involving nanofilled composite resins. Material polymerization factors and water absorption can affect the hardness of composite resins. Imperfect polymerization producing an oxygen inhibited layer (OIL) and causing water absorption can even compromise the hardness of nanofilled composite resins. Tamarind soft drink, on the other hand, has an acidic pH that compromises the hardness of nanofilled composite resins. Purpose: This study aimed to reveal the effects of glycerin application on the hardness of nanofilled composite resins immersed in tamarind soft drinks. Methods: The research constituted a laboratory experiment using 24 nanofilled composite resin samples with diameters of 5mm or 2mm, divided into six groups, namely: Group G, Group G AS 60, Group G AS 120, Group TG, Group TG AS 60, and Group TG AS 120. Glycerin was applied to the surfaces of three groups before curing, while the other three groups were not treated with glycerin. Finishing was subsequently conducted on all samples using a highspeed handpiece and superfine finishing bur, before they were polished with a low speed handpiece. The samples were then divided into specific groups, namely: a group with a 120-minute immersion time, a group with a 60-minute immersion time, and a group which was not immersed and maintained at a temperature of 37oC. Each sample was tested at three points using a Vickers hardness tester (VHT). Results: The results showed that the groups with glycerin had a higher hardness level than those groups. In addition, the non-immersed groups had a higher hardness level than those groups which were immersed. The one-way ANOVA test results confirmed that there was a statistically significant difference (p<0.05) between all groups. Conclusion: The application of glycerin to nanofilled composite resins immersed in tamarind soft drinks can increase their hardness levels.

Analisa Kekasaran Permukaan Pada Proses Edm Sinking Menggunakan Metoda Response Surface Methodology

The development of technology in the manufacturing sector is very fast, the market demand is diverse will the needs of products and components with complex shapes and high level of precision and hardness of material that has high strength. High degree of hardness and precision are widely used nonconventional EDM machine sinking. the electrode wear rate (LKE) and surface roughness (KP) are at least the performance of the EDM sinking machine process to be achieved. The study was conducted to determine the contribution of process parameters in order to reduce the variation of response parameters simultaneously and to determine the appropriate process parameter setting value. Parameters varied current, on time, off time and machining voltage. This research uses experimental design from Response Surface Methodology (RSM) method. And obtained the most refined Ra roughness results on Ton 100 µs, and Toff 15 µs with 10 A Ampere, and the roughest Ra roughness is obtained at Ton 300 µs, and Toff 15 µs with Ampere 20 A.

Physiochemical Analysis of Community Water Supply in Kathmandu Valley

This study was carried out to assess groundwater quality of the Kathmandu Valley, Nepal, because Safe drinking water is a basic need of all humans and to protect the human health, community water suppl y must be reliable, adequate and readily accessible to all segments of the consumers. For this the groundwater samples from eight different regions of the valley were collected during months of Jun-Jul in the year 2018. Th ese collected groundwater samples were analyzed various physio-chemical parameters such as temperature, colour, turbidity, pH, electric conductivity (EC), total alkalinity, phenolphthalein alkalinity, total hardness, iron, chloride,Nitrate and total ammonia using the procedure outlined in the standard methods. Results showed that the water quality status was found to vary from place to place. High levels of turbidity, total alkalinity, total hardness, iron and total ammonia were found in the groundwater of many sites. The results were compared with WHO water quality guideline and National Drinking Water Quality Standard (NDWQS) of Nepal.

Microstructural evolution of a dual hardening steel during heat treatment

Dual hardening steels combine precipitation of both secondary hardening carbides and intermetallic phases in a martensitic matrix. Due to this combination, the carbon content necessary to achieve high hardness levels can be reduced, resulting in a decreased amount of large and embrittling carbides.In this study, the influence of different heat treatments on microstructure evolution and secondary hardness is investigated. Different metallographic preparation methods were tested in order to visualize the microstructure. Carbides were characterized using spot-pattern electron backscatter diffraction.For light optical investigations, preparation with V2A-pickle lead to the best results. Preparation with colloidal silica suspension achieved the best results for investigations by scanning electron microscopy and for carbide characterization using electron backscatter diffraction. It was found that a homogenization treatment prior to austenitization was unable to increase the amount of dissolved carbides, and thus had no effect on secondary hardness. By increasing the austenitization temperature, the amount of carbides and secondary hardness could be increased significantly.

Structure and Characteristics of the Metal of the Cr-Ni-Mo-Mn-Si-Ti-Nb System Obtained by Surfacing with a Flux-Cored Wire Alloyed by Boron Carbide

This study explores structure and characteristics of the nickel-chrome steel of the Cr-Ni-Mo-Mn-Si-Ti-Nb-B doping system obtained by surfacing with a flux-cored wire alloyed by boron carbide. It has shown that the deposited metal has a composite structure consisting of a supersaturated with alloyed elements solid solution with an austenite-martensitic matrix and a eutectic component (Mo, Cr, Fe, Nb)2B in the form of sections along the boundaries of former austenite grains. Because of the significant content of ferrite-forming elements in the process of crystallization, a metastable δ-ferrite is formed in the weld metal in the form of differently oriented interlayers between the martensite rails. As a result of aging of such a deposited metal at 500 °C for 2 hours, the metastable ferrite undergoes decay at the interphase boundaries α/δ with the formation of the σ phase, which represents sharpened plates with the size of 300÷550 nm. Moreover, aging leads to hardening of the matrix by finely dispersed carboboride and intermetallic phases (Cr, Mo, Fe, Nb, Ti)23(С,В)6, (Fe, Cr, Si)2(Mo, Ti) и (Ni, Fe)3Ti, causing high levels of hardness and wear resistance. The usage of this wire as a surfacing material allows to increase significantly the operability and reliability of the stop valve parts, which work on abrasion in contact with corrosive medium.

Physico-chemical Properties Tests of Palm Oil Based Foaming Agent Using Water Solvent Media from Peatland

The water supply requirement to extinguish the fire on the occurrence of land fires is enormous. The water used is usually water available in the field, without certain parameter requirements. For frequent peatland fires, the available peat water in the field becomes an option for use in dissolving the tested foaming agent. Indonesia has a peat land area that has a very large water storage capacity of peat soils. Peat water is the surface water of peat soil with characteristic of brownish red color, contains high organic matter, high iron content, acid taste, pH 3-5 and low level of hardness. This study aimed to determine the effect of peat water use as a solvent on the physico-chemical properties of foaming agent concentrate made from palm oil. Tests were performed using two types of foaming agent concentrate products (CFA-1 and CFA-2) with foaming agent concentrates used were 1, 2 and 3%, and well water was used as a comparison (control). The analysis results showed that the use of peat water as a solvent for palm foaming agent concentrate can be done because it still produces high foam stability, high foaming ability, low interfacial tension, and high decrease of contact angle, as well as the use of well water. The analysis results of CFA-1 using peat water were not quite different from those of CFA-2.

High hardness and low dielectric constant thin films with oriented urea oligomers by physical vapor deposition

Oligomers of undecylurea (OUA11) thin films with a high crystallinity, surface hardness, perpendicular orientation, and low dielectric constant were fabricated by physical vapor deposition. The thin films were composed of single OUA11, which has a relatively high molecular weight (Mw: 2500, Mn: 1200) and could be vapor-deposited without thermal decomposition. These films had a much higher crystallinity and a high surface hardness level of 9H in the pencil hardness test. The dielectric constant of the OUA11 films is estimated to be 2.1–2.3 in the frequency range of 1 Hz–0.1 MHz, which is lower than that of typical low dielectric constant (low-k) materials. These physical and electrical properties are caused by the unique structure with the molecular dipoles-oriented parallel to the electrodes on the substrate and the strong intermolecular hydrogen bonds. The unique structure could not be observed with spin-coating and is specific to the vapor-deposited films. We expect that the OUA11 films with a high hardness and a low dielectric constant can be used not only as protective coatings but also as electronic materials.