The surface hardening of mild steel by carburization using periwinkle shell nanoparticles (PWSnp) and coconut shell (CS) was investigated. The carburization was done at 850, 900, and 950 °C with a ratio of PWSnp:CS of 1:9, 2:8, and 3:7. The case depth, hardness values, wear, and corrosion rates were determined. A 114.1

In this study, different sizes (25, 50, and 75 µm) and volume fractions (1, 2, and 3 wt%) of calcined eggshell particles were utilized to strengthen the Al-Si-Mg alloy. Several experimental runs were conducted to assess the impact of particle size and concentration on both physical properties (density, corrosion, and thermal conductivity) and mechanical properties (hardness, yield strength, impact energy, and modulus of elasticity). The findings revealed significant enhancements in hardness (21 %), yield strength (61 %), modulus of elasticity (43 %), and thermal conductivity (34 %). Conversely, a reduction of 62 % in impact strength and 8 % in density was observed. The corrosion rate displayed an increase from 0 to 16.67 mpy. Analysis using XRD and XRF techniques identified CaO and Al2O3 as the primary constituents of the eggshell. Optical micrographs consistently showed cored (segregated) dendritic structures typical of castings cooled under normal conditions in the Al-Si-Mg composite. SEM micrographs, EDS spectra, and area analyses confirmed a uniform distribution of Calcined Eggshell Particles (CEP) within the composite films. Additionally, an optimal calcination condition for the eggshell particles was determined to be 900 °C for 2.5 h, resulting in a CaO yield of 99.62 %.

The study considered the effect of welding electrode composition on the mechanical and corrosion integrity of welded AISI 2205 duplex stainless steel in a chloride environment. For the electrode coating, two fluxes were developed: basic and acidic fluxes, with basicity indexes of 2.40 and 0.40, respectively. To confirm the thermal stability of the flux ingredients, thermogravimetric analysis was conducted. Different applicable standards were used to evaluate the chemical composition, mechanical, microstructural, and corrosion characteristics of the welded joints. In terms of the ultimate tensile strength, welded joints with electrodes coated with basic flux (E1) had a higher basicity index than those coated with acidic flux (E2). This pattern was also visible when comparing the Vickers hardness of welded joints made with electrodes E1 and E2 to joints made with electrode C (control sample). An increase in amperage from 90 to 110 A increases the heat input required for welding, which in turn affected the weldments' ability to resist corrosion in a chloride environment.

Mild steel is made of iron and other elements, the chief among which is carbon. It is considered one of the most notable alloys in engineering applications because of its high tensile strength advantage and low cost. However, mild steel essentially lacks the hard surface quality which is considered key to many structural and industrial applications. This review explores various aspects of the carburization of mild steel which is targeted at providing the hard surface quality it lacks. This work critically reviews the mechanisms of different carburization methods, factors affecting carburization quality, and the potential of organic additives for carburizing low-carbon steel. Furthermore, this review article provides new insights into organic energizers and their benefits to both the handlers of carburizing operations and the environment in which they are carried out, following the United Nations' Sustainable Development Goal number 12 on sustainable production and consumption. Finally, this review concludes by providing directions for future research on organic additives-based mild steel carburization.

The surface hardening of mild steel by carburization using periwinkle shell nanoparticles (PWSnp) as an energizer and coconut shell ash (CS) as a carburizer was investigated. For the carburization process, PWSnp:CS ratios of 0:0, 1:9, 2:8, and 3:7 were used. The hardness values, corrosion rate, and microstructure of the samples were determined. The results show a 114.1% increase in hardness values and corrosion protection efficiencies of 95.64 and 92.58%, respectively, at 3:7PWSnp:CS in 1 MH2SO4 and 35 wt% NaCl. Less corrosion damage was seen in carburized samples because the hard phases provided resistance to the corrosion's destructive activity. It was established that waste periwinkles shell and coconut shell can be used for surface hardening of mild steel.

Over the years, hydroxyapatite (HAp) has been a well-researched biomaterial because of its bioactive and biocompatible properties with remarkable applications for bone tissue engineering. The robust structure of HAp allows for a host of applications in biomedicine. HAp is enriched in calcium and phosphate, can be sourced from synthetic or natural precursors with significant characteristics notable of biomaterials, and can be produced by facile protocols for clinical use. Nonetheless, HAp prepared from natural or synthetic sources are different due to the conditions of processing. One of the factors in this direction and for the high performance of bioceramics in biomedicine is a robust mechanical strength that prevents failure of the HAp scaffolds. Stemming from these, and of particular interest, is the porosity of the HAp-derived scaffolds that plays a major role in the mechanical properties in vitro and in vivo. Many reports have it that there are reduced mechanical properties vis-à-vis the inherent high porosity of the scaffolds, and these must be balanced in line with the degradation rate of the scaffolds. Gradients in pore sizes and crack propagation tendencies are important to lead to new production methods with the potential to generate scaffolds with morphological and mechanical properties designed to meet bone repair needs. Nowadays, validating mechanical and materials engineering properties with the aid of atomistic simulations using density functional theory (DFT) and artificial intelligence (AI), and the complement of experimental studies, is gradually becoming an important research domain within the scientific community. The importance of these theoretical and AI methods can be ascribed to the comprehension of the non-linear relationship between some measured properties using experimental datasets. Hence, this review explores a re-cap and the state of knowledge regarding sustainable natural sources of HAp, data on mechanical property measurements, the link between porosity and mechanical properties of HAp-derived materials for bone tissue engineering, a relatively new method for characterizing the mechanical behavior of HAp, computational trends in biomaterials research, and recent trends on the biomedical applicability of HAp.

Mechanical and corrosion properties of welded duplex stainless steel (DSS) structures are of paramount consideration in many engineering applications. The current research investigates the mechanical properties and corrosion integrity of duplex stainless-steel weldment in a simulated 3.5% NaCl environment using specially developed novel electrodes without the addition of alloying elements to the flux samples. Two different types of fluxes having basicity indexes of 2.40 and 0.40 were used to coat E1 and E2 electrodes respectively for DSS plate welding. The thermal stability of the formulated flux was evaluated using thermogravimetric analysis. The chemical composition, using optical emission spectroscopy, and the mechanical and corrosion properties of the welded joints were evaluated as per different ASTM standards. X-ray diffraction was used to find out the phases present in the DSS welded joints while a scanning electron equipped with EDS was used for microstructural examination of the weldments. The ultimate tensile strength of welded joints made using the E1 electrode was in the range of 715–732 MPa and that of the E2 electrode was found to be 606–687 MPa. The hardness was increased with increased welding current from 90 to 110 A. The welded joint with E1 electrode coated with basic flux has better mechanical properties. The steel structure in 3.5% NaCl environment possesses substantial resistance to corrosion attack. This validates the performance of the welded joints made by the newly developed electrode. The results are discussed on the basis of the depletion of alloying elements such as Cr and Mo observed from the weldments with the coated electrodes E1 and E2 as well as precipitation of the Cr 2 N in the welded joints made by E1 and E2 electrodes.

This research tends to investigate the influence of shielded metal arc welding (SMAW) parameters and flux compositions on the metallurgy of welded AISI 2205 duplex stainless steel (DSS). The consumable was developed using the Al2O3-TiO2-SiO2 flux system as major flux ingredients. The spectrophotometer was used for determining the chemical composition of the base core wire and the base plate. The six different fluxes (F1, F2, F3, F4, F5 and F6, with varied compositions were coated on a 3.2 mm diameter of ER2209 core wire with a coating factor of 1.65 mm. Basicity indexes of the six formulated fluxes were calculated to be less than 0.9 for the developed electrodes, which confirmed the electrodes to be acidic coated electrodes. The influence of welding parameters, particularly current on the hardness characteristics of the weldment was established to ascertain the integrity and applicability of the developed consumable. It was evident that the average welding current of 120A at a constant voltage of 22.5 V produced high hardness properties of the welded joint of DSS with an optimal heat input of 1.65KJ/mm. The hardness properties in most sceneries were observed to be high at heat affected zone (HAZ) and fusion zone (FZ) than in the base metal (BM) region which is attributed to the ferrite content. The average hardness value of the BM was found to be 241Hv/20, for the FZ and HAZ using the produced electrode F5 and F6 were found to be 250HV/20 and 301HV/20 respectively and for F6 was found to be 259HV/20 at FZ and 336HV/20 at the HAZ while that of the commercial electrode (C) was found to be: FZ-245/HV/20 and HAZ-319/HV/20 which is a good indication of its conformity to standard DSS. The SEM-EDS morphological characterization also reveals the austenite-ferrite phase with relatively coarse grains, inter-critical grains and fine grains at the HAZ regions of the welded joint. (c) 2021 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the Global Conference on Recent Advances in Sustainable Materials 2021.

This study describes the mechanical properties of pure hydroxyapatite (HAp) and kaolin reinforced hydroxyapatite (K-HAp) produced from non-separated animal bones using compression pressure under different sintering regimes. The HAp microparticles were synthesized separately using a facile heat treatment method and reinforced with 15 wt% of beneficiated kaolin (HAp/15 wt% BK) using the sol-gel method. The HAp and K-HAp derived scaffolds were fabricated by cold pressing with a compaction pressure of 500 Pa. Next, the scaffolds were sintered at 900 degrees C, 1000 degrees C and 1100 degrees C with a 2 h dwell time in air atmosphere. Subsequently, the mechanical properties of the scaffolds were examined. The effect of sintering temperature and compaction pressure on the hardness and the compressive strength of the pure and reinforced HAp showed that at all points of measurement (with and without compaction pressure), the mechanical properties increased with an increase in sintering temperature, and the most significant mechanical properties were obtained at 1100 degrees C. The values of hardness at the maximum sintering temperature (1100 degrees C) are 0.93 and 1.09 GPa with and without the application of compaction pressure, respectively, for pure HAp-derived scaffolds and 0.74 and 0.78 GPa with and without the application of compaction pressure, respectively, for K-HAp-derived scaffolds. The compressive strength for K-HAp had the value of 7.84 MPa as compared with 0.69 MPa for the non-reinforced HAp matrix with the application of compaction pressure (500 Pa). The findings show that the mechanical properties of the synthesized kaolin reinforced HAp in relation to the scaffolds produced with the low compaction pressure of 500 Pa is suitable for human trabecular bone. (C) 2020 The Authors. Published by Elsevier Ltd.

Duplex stainless steels (DSSs) structures, especially the American Iron and Steel Institute (AISI)type 2205 and 2507 have greatly attracted the attention of many researchers, engineers, manufacturers as well as the end-users of the productsbecause of its superior engineering properties like strength, good toughness, particular resistance to corrosive environments and to stress corrosion cracking (SCC). Due to its worldwide progressive growth, demand and utilization, this novel steel (DSS) is rising very fast, especially in marine, power plants, chemical process, mining, petrochemical, oil and gas, pharmaceutical and many other related engineering applications. Generally, the joining of DSSs alloys is a big problem due to its susceptibility to sensitization caused by the precipitation of additional phases when heated above 600°C. Conversely, improper selection of welding parameters, imbalance ratio of austenite/ferrite phases can lead to corrosion susceptibility, solidification cracking and susceptibility to plastic deformation. Shielded metal arc welding (SMAW) technique with recommended consumables (E2209 and E2594 or E2595) is used in the fabrication of the multiphase steels with the aim of obtaining the optimum weldment with the desired input welding criteria, optimum mechanical properties with minimum defects from the microstructural perspective and excellent corrosion behaviours. This review is therefore geared towards accentuating the influence of arc welding processes, and SMAW in particular on the microstructure, mechanical and corrosion properties of DSSs weldment.

The solution combustion route was used to fabricate strontium (Sr) doped hydroxyapatite (HAp). A low compaction pressure method was adopted for pelletizing the powders (Sr-HAp) prior to physical and mechanical properties measurement. Physiological stability of the pellets was conducted by immersing in Phosphate Buffer Saline (PBS) solution for 24 h. The Sr-HAp produced a comparatively higher hardness and fracture toughness of 0.38 GPa and 0.82 MPa.m(1/2) compared with 0.20 GPa and 0.67 MPa.m(1/2) for undoped HAp. The SEM images suggested that strontium co-existed with the calcium ion in hydroxyapatite due to the presence of irregular bead-like structures on a micro-scale. The Sr-HAp pellets were stable in Phosphate Buffer Saline solution.

Comparative study of kaolin reinforced hydroxyapatite (KHAp) and pure HAp using different production parameters has been done through traditional experimentation. However, the quantitative effect, optimization of kaolin reinforcement and fabrication parameters have not been investigated. Hence, this study examines the effect of kaolin reinforcement, compaction pressure and sintering temperature on the experimental mechanical properties of HAp. Taguchi design assisted by grey relational analysis was employed with L36 (2**2 3**1) orthogonal array. The Minitab 16 software was used to analyze the Taguchi design. The result showed a disparity in kaolin reinforcement as the optimum condition for individual mechanical properties, but the grey relational analysis showed better mechanical properties with kaolin reinforcement, 500 Pa compaction pressure and 1100 oC sintering temperature. The obtained result further revealed kaolin reinforcement as a strong and promising reinforcing material for high strength clinical application, having a contribution of 93.16% on compressive strength of HAp. Therefore, future studies can be conducted in the use of different wt% of kaolin on the multi-response mechanical characteristics of HAp.

In this study, hydroxyapatite (HAp) microparticles obtained from animal bones were synthesized, and for the first time, HAp was reinforced with beneficiated kaolin using the sol-gel route to improve the mechano-biological properties of the bioceramic materials. The non-reinforced HAp as well as the reinforced samples (K-HAp) were sintered at 900, 1000 and 1100 degrees C to consolidate the mixture and detailed physico-chemical and mechanical characterizations was conducted. In-vitro experiments in phosphate buffer saline and simulated body fluid were used to confirm the degradability and compatibility of the HAp-derived bioceramic materials, respectively. XRD signatures showed that a dominant phase of hydroxyapatite was formed at all sintering temperatures (900, 1000, 1100 degrees C). The calcium to phosphate ratio (Ca/P) of the K-HAp-900 sample was approximately 1.67, which is the Ca/P ratio for stoichiometric hydroxyapatite prepared from synthetic sources. The active surface areas of the produced kaolin reinforced bioceramic materials: K-HAp 900-1100,were 0.9770, 0.2159 and 0.8659 m2/g, respectively, while the obtained micropore volumes were 0.000397, 0.001287, and 0.000334 cm3/g, respectively. At 900, 1000 and 1100 degrees C, compressive strengths (after applying the compaction pressure) with a value of 5.67, 6.33 and 7.66 MPa were obtained for the kaolin reinforced bioceramic materials, respectively. The mechanical measurement data further confirms that the reinforced bioceramic materials are suitable for human trabecular bone as the proposed scaffolds were endowed with an improved mechanical strength matching the bearable range of trabecular bone (2-12 MPa). In-vitro experiments showed the degradability and compatibility of the scaffolds. A relative neutral pH was maintained for sample K-HAp 900, and this sample also showed inhibitory potentials for bacterial strain (E. Coli).

The quenching ability of modified and unmodified cottonseed oils was investigated using AISI 1070 steel. In the event of the quenching, the steel samples immersed in each of five distinct quench media, namely epoxidized cottonseed oil (EC), epoxidized-transesterified cottonseed oil (ETC), transesterified cottonseed oil (TC) and fresh cottonseed oil (FC). Tests and analysis conducted determined mechanical properties and microstructures of the quenched samples. The data obtained showed that ETC outperformed other quench media with hardness value of the quenched sample; 407 HVN (hardness value from the FC-quenched sample) increased to 746 HVN indicating an 83.29% improvement. Notably, in the microstructure of ETC-quenched sample, a unique homogeneous microstructure containing a mixture of lath and plate martensite observed with largest martensite per cent of 95.

There is a growing interest for novel materials of dissimilar metals due to higher requirements needed for some critical engineering applications. In this research, different dissimilar weld joints of high strength low alloy (HSLA) and 316 austenitic stainless steel grades were successfully produced using shielded metal arc welding (SMAW) process with 316L-16 and E7018 electrodes. Five variations of welding currents were employed within the specified range of each electrode. Other welding parameters such as heat inputs, welding speeds, weld sizes, arc voltages and time of welding were also varied. Specimens for different weld joint samples were subjected to microstructural studies using optical and scanning electron microscopes. The impact toughness test was also conducted on the samples using Izod impact testing machine. The analysis of the weld microstructures indicated the presence of type A and AF solidification patterns of austenitic stainless steels. The results further showed that the weld joints consolidated with E7018 electrode presented comparatively superior impact energy to the weldments fabricated by 316L-16 electrode. The optimum impact energy of E7018-weld joints (51J) was attained at higher welding heat inputs while that of 316L-16-weld joints (35J) was achieved at lower welding heat inputs, which are necessary requirements for the two electrodes used in the experiment. Hence, the dissimilar weld joints investigated could meet requirement for engineering application in offshore and other critical environments.Keywords—Dissimilar metal weld, heat input, impact toughness, microstructures

The wear and mechanical properties of aluminium alloy (Al-Si-Mg)/ locust bean waste ash particles composites developed by stir casting were studied. The composites were based on the A356 alloy reinforced with locust bean waste ash (LBWA) particles. X-ray fluorescence (XRF) analysis on the LBWA particles was carried out. The mechanical properties tested are hardness, tensile strength and impact energy while the wear behaviour of the developed composites was studied by conducting dry sliding wear test using a ball-on-disc tribometer. Results revealed that there is a high influence of reinforcement addition on the tested mechanical properties. The wear rate decreased significantly with increasing weight fraction of LBWA particles. The highest hardness, tensile strength and wear resistance are obtained with the addition of 10% wt. LBWA particles.

In this research, dissimilar weld joints of 316 stainless steel/HSLA steel were produced using ER316L-16 and E7018 filler metals by varying welding parameters such as current and arc voltage. Heat input and travel speed was computed. The joints were subjected to tensile test and tensile values were determined, computed, recorded and analysed. The heat inputs were compared with the tensile test results. According to the results obtained and analysis carried –out the weld joint of E7018 (E) filler metal presented optimum ultimate tensile strength of 498 MPa at higher heat input of 3.32 kJ/mm while the weld joint of ER316L-16 (L) filler metal offered optimum ultimate tensile strength of 450 MPa at lower heat input of 1.66 kJ/mm. The optimum percent elongation of ER316–16 is 15% while that of E7018 is 19.5%. The results were compared with related previous works. Tensile strengths of specimen L and E are superior to that of HSLA steel but inferior to 316SS in as-received condition proving that the weld joints are satisfactory and meet requirements for engineering applications.

The purpose of the dataset is to present the morphological features, elemental composition and functional groups of hydroxyapatite (HAp) synthesized from non-separated biowastes (animal bones) by a modified facile heat treatment method up to a maximum temperature of 1100 degrees C. The synthesized powders were characterized using scanning electron microscopy (SEM) equipped with electron dispersive X-ray analysis (EDX) and Fourier transform infrared spectroscopy (FTIR). These evaluations were to reveal the surface features, elemental composition and identify the functional groups of the synthesized powders. After heat treatment of the raw biowastes to 900 degrees C, 1000 degrees C, and 1100 degrees C (regime of heat treatment), the morphological features of the samples exhibited a more densely packed microstructure at the highest sintering temperature (1100 degrees C). The elemental composition as evaluated by EDX on a weight and atomic basis for all samples provided information on the calcium to phosphate transforms into apatite with a Ca/P ratio of 3.60, 2.04, 2.50 and 2.32 wt % and 2.79, 1.58, 1.94 and 1.78 at. % respectively for raw biowastes (RB) to sintered samples (HA-900, HA-1000 and, HA-1100 degrees C). The FTIR data showed phosphate and hydroxyl peaks in the thermally treated samples and all the samples produced characteristic stretching modes of O-H bands at about 3417 cm(-1) which are noticed in all FTIR spectra of HAp. (C) 2019 The Authors. Published by Elsevier Inc.

This study describes the effect of sintering temperature on the microstructural, calcium/phosphorus (Ca/P) ion ratios and mechanical properties of non-separated biowastes processed hydroxyapatite (HAp) prepared through a low cold compaction protocol. The HAp was produced by a sintering temperature of 900 degrees C. Furthermore, HAp sintered at 900 degrees C was subjected to sintering temperatures of 1000 and 1100 degrees C.The structural and morphological evolution of the fabricated biomaterials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with electron dispersive X-ray analysis (EDX) respectively. Uniaxial compaction using a pressure of 500 pa was used to produce rectangular shaped pellets to investigate the influence of sintering temperature on the mechanical properties of the produced pellets. Prom XRD analysis, it was found that hydroxyapatite derived from the biowastes showed good thermal stability and did not exhibit phase instability with traces of other calcium phosphates. The SEM micrographs showed microporous structure of the biomaterials and an increase in temperature reduced the porosity and enhanced the mechanical properties. It was also noticed that the trend of transformation of the average shape of pores was from strongly flattened to round at higher sintering temperatures. Electron dispersive X-ray analysis (EDX) revealed that the atomic Ca/P ratios of the as-sintered HAp specimens ranged from 1.58 to 1.79 for sintering temperatures of 900-1100 degrees C. The synthesized hydroxyapatite powder showed inclusion of the fluorapatite phase at sintering temperature of 1000 degrees C with a reduction in the crystallite size. For both scenarios (sintering temperature and compaction pressure), a consistent trend in mechanical properties (microhardness, fracture toughness and Young's modulus) is noticed at every point of measurement except for compressive strength. The reduction in compressive strength when compaction pressure was applied could be as a result of the stress induced in the HAp powders during compaction which may have made it more susceptible to cracks. The hardness value obtained for the synthesized hydroxyapatite pellets is in the range of that of actual human femoral cortical bone.

This study investigates the possibility of multi-objective optimization in the transesterification of mahogany seed oil (MSO). The Taguchi method together with Grey relational analysis (GRA) was used to maximize both percent fatty acid methyl ester (FAME) yield and heat transfer coefficient (HTC). It was found that methanol to oil molar ratio was the factor that contributed the most in obtaining high percent FAME (ester) yield and HTC. Employing the following conditions: 32.6 wt% methanol (9:1 methanol to oil molar ratio), 0.5 wt% catalyst, 60 °C temperature and 300 rpm agitation was found to offer an improved percent ester yield and HTC. A confirmatory test resulted in an ester yield of 90.1 % and HTC up to 153.0 W/m2K. The structure of the optimized transesterified mahogany seed oil (TM) was confirmed by FTIR analysis. In the event of comparison, TM, raw mahogany seed oil (FM) and SAE40 were analyzed by cooling curve analyses. TM identified to have superior quenching performance.