HA Powder Research Articles

Characterization of marine hydroxyapatite and its interest in bone filling in rabbits femoral defect model: In vivo, in vitro, and in silico study

PurposeHydroxyapatite (HA) is a promising scaffold material for bone defect treatment. This study aimed to evaluate the physicochemical and biological properties of a novel marine-derived HA extracted from blue fish scales and assess its potential as a bone substitute for clinical use. Methods80 female New Zealand white rabbits were assigned to 4 groups (n = 20): HA powder (EC group), 3D-printed HA cylinder (I3DFFF group), negative control group (NC group; bone defect without biomaterial), and positive control group (PC group; bone defect treated with commercially synthesized HA). The biomaterials were characterized in vitro using X-ray diffraction, nitrogen adsorption, scanning electron microscopy, emission spectrophotometry, and MTT assays. In vivo evaluation involved the same techniques, supplemented with histological and radiological analyses at 1, 3, 6, and 9 months post-implantation. Molecular docking studies were also performed to investigate HA's effect on RANKL-induced osteoclastogenesis and the NF-κB signaling pathway. ResultsIn vitro characterization showed that marine-derived HA is a mesoporous material with a crystalline structure similar to natural bone. In vivo, the material demonstrated biocompatibility, osteoinductivity, and osteoconductivity, providing a supportive environment for bone regeneration. Molecular docking indicated that HA could inhibit osteoclastogenesis by suppressing the NF-κB signaling pathway. ConclusionOur findings suggest that the two co-products, EC-17 and I3DFFF, possess the necessary physicochemical and biological characteristics to be developed as effective bone substitutes.

Antibacterial and cytotoxic effects of fresh bovine amniotic membrane with hydroxyapatite (BAM-HA): a laboratory experiment

Introduction: Bacterial infections, particularly by Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) and Porphyromonas gingivalis (P. gingivalis), can worsen alveolar bone resorption after tooth extraction. The capability of Bovine Amniotic Membrane-Hydroxyapatite (BAM-HA) biocomposite to reduce this resorption has been explored. However, before clinical use, cytotoxicity testing is imperative to ensure its biocompatibility. The aim of the study was to assess both the antibacterial effects and cytotoxicity of the BAM-HA biocomposite to ensure its suitability for clinical use biocompatibility of the BAM-HA biocomposite before its clinical application. Methods: The laboratory-based research involved testing BAM combined with HA powder in 4:1 and 4:2 ratios via freeze-drying and underwent antibacterial tests against A. actinomycetemcomitans and P. gingivalis, using the plate count method. Cytotoxicity tests were performed on HGF cells, including negative control, positive control, BAM-HA (4:1), and BAM-HA (4:2) groups, with statistical analysis conducted using One-Way ANOVA and Post Hoc Bonferroni and Tukey tests. Results: Antibacterial tests against A. actinomycetemcomitans revealed significant reduction in colony count with BAM-HA ratios 4:1 (129.0 ± 12.7 CFU/mL) and 4:2 (77.3 ± 15.5 CFU/mL) compared to the negative control (186.6 ± 27.5 CFU/mL). Similar reductions were observed for P. gingivalis, with BAM-HA ratios 4:1 (51.3 ± 6.6 CFU/mL) and 4:2 (3.1 ± 1.5 CFU/mL) compared to the negative control (117.3 ± 22.0 CFU/mL). Cytotoxicity tests showed no significant differences in HGF cell viability and IC50 values between the negative control and BAM-HA (4:1) or BAM-HA (4:2) groups. Conclusion: The BAM - HA biocomposite shows antibacterial effects against A. actinomycetemcomitans and P. gingivalis. Moreover, BAM - HA ratios of 4:1 and 4:2 do not induce cytotoxic effects on human gingival fibroblasts, suggesting potential biocompatibility for clinical applications.KeywordA. actinomycetemcomitans, antibacterial effects, BAM-HA biocomposite, cytotoxicity, P. gingivalis

Moldability and Solvent Debinding of Hydroxyapatite Micro-Part Processed through Micro-Powder Injection Molding

The development of the micro-powder injection molding (µPIM) process from the powder injection molding (PIM) process has been prompted by the demand of the worldwide market to produce micro-sized components. The need for µPIM-processed components is currently rising across a range of industries, including automotive, aerospace, food, biomedical, electronics, and telecommunications. In the current research work, homogeneous HA feedstock with a powder loading of 57 vol.% was prepared by mixing HA powder particles with palm stearin and low-density polyethylene (LDPE) binders at a mixing temperature of 150 °C for 6 h. Defect-free injection molded or green micro-sized components of HA were produced by employing injection pressure, injection time, mold temperature, and melt temperature of 12 bar, 5 s, 110 °C, and 180 °C, respectively. When mold temperatures less than 110 °C were used, short shot defects were frequently observed in green specimens. After solvent debinding at 60 °C for 50 min, 82.2% of the palm stearin was removed from the green part. No difference in dimension between the solvent debound part and the green part was noticed. An open-pore structure developed in the solvent debound HA microcomponent is helpful for eliminating the insoluble LDPE binder during the thermal debinding phase.

In vivo study on osteogenic efficiency of nHA/ gel porous scaffold with nacre water-soluble matrix

Background/purposeNano-hydroxyapatite (nHA)/ gel porous scaffolds loaded with WSM carriers are promising bone replacement materials that can improve osseointegration ability. This investigation aimed to evaluate the osteoinductive activity by implanting the composition of nano-hydroxyapatite (nHA)/ Gel porous scaffolds as a carrier of WSM via an animal model. Materials and methods: WSM was extracted and nHA was added to the matrix to construct porous composite scaffolds. The dose-effect curve of WSM concentration and alkaline phosphatase (ALP) activity was made by culturing rat osteoblasts and examining the absorbance. Three different materials were implanted into critical size defects (CSD) in the skulls of rats, which were further divided into four groups: WSM nHA /Gel group, n-WSM nHA /Gel group, HA powder group, and control group. Results: WSM (150 μg/mL-250μg/mL) effectively improved the activity of ALP in rat osteoblasts. All rats in each group had normal healing. WSM-loaded nHA /Gel group showed better performance on newly-formed bone tissue of rat skull and back at 4th week and 8th week, respectively. At the 4th week, the network of woven bone formed in the WSM-loaded nHA/Gel scaffold material. At 8th week, the reticular trabecular bone in the WSM-loaded scaffold material became dense lamellar bone, and the defect was mature lamellar bone. In the subcutaneous implantation experiment, WSM-loaded nHA/Gel scaffold material showed a better performance of heterotopic ossification than the pure nHA/Gel scaffold material. Conclusion: WSM promotes osteoblast differentiation and bone mineralization. The results confirm that the nHA/ Gel Porous Scaffold with Nacre Water-Soluble Matrix has a significant bone promoting effect and can be used as a choice for tissue engineering to repair bone defects.

Densification of hydroxyapatite through cold sintering process: Role of liquid phase chemistry and physical characteristic of HA powder

Hydroxyapatite is a well-known bioactive material widely employed in bone regeneration applications. Densifying hydroxyapatite at the nanoscale remains challenging with conventional sintering methods. This investigation focuses on the densification of commercially available nano-hydroxyapatite powders through the cold sintering process, utilizing water, acetic acid, and phosphoric acid solutions as transient liquids under 360 MPa pressure at 200 °C. The study systematically examines the influence of physical parameters of hydroxyapatite powder, liquid nature, and ionic concentrations of acid solutions on densification and microstructural characteristics. The relative density of consolidated samples varied with respect to the ionic concentration of the acid solution. Notably, a maximum relative density of 90% has been achieved for hydroxyapatite cold sintered using 2 M phosphoric acid solution without changing the original phase of hydroxyapatite. Overall, this study offers valuable insights into the impact of liquid chemistry on the densification of hydroxyapatite using the cold sintering technique.

Use of Multi-pass FSP treatment for improving mechanical properties and corrosion resistance of Mg-2Zn-HA composite

Magnesium (Mg) alloys are very popular among the biomaterials for biodegradable bone implants due to their suitable properties matching with that of human cortical bone. However, their poor corrosion resistance in biological fluid is a major constraint to become an ideal choice for bioimplants. The corrosion resistance of Mg-alloys is further retarded with microstructural impurities such as micro-pores, micro cracks, heterogeneous distribution of alloying element etc., which is commonly present in as-cast Mg-alloys. In present study, Friction stir processing (FSP) has been performed on Mg-2Zn alloy to refine the microstructures as well as to develop Mg-Zn-HA composites by using HA powder reinforcement. HA powder reinforcement was added using micro-grooves and multiple FSP passes on as-cast Mg-2Zn alloy having average grain size of 63.86 µm. Filling HA powder in 2-grooves and using 3-pass FSP, a refined microstructure having an average grain size of 7.15 µm and homogeneous distribution of HA powder was obtained for the developed Mg-Zn-HA composite. The Mg-Zn-HA composite developed with 3-pass FSP treatment has shown significant improvement in tensile strength and corrosion resistance as compared with as-cast Mg-alloy.

Microstructure, Mechanical Properties, In Vitro Biodegradability, and Biocompatibility of Mg-Zn/HA Composites for Biomedical Implant Applications.

Recently, Mg-Zn/hydroxyapatite (HA) composites have attracted much attention as potential candidates for use in bone implants. In this paper, the MgZn/HA composites were prepared using powder metallurgy (PM) and the merging mechanism of MgZn and HA particles was investigated by adjusting the weight ratio of the HA powder. The evolution of the HA distribution in the matrix was examined using SEM and micro-CT images. Afterward, the mechanical properties and biocompatibility of the composites were discussed in detail. The results revealed that the mechanical properties and biocompatibility of the Mg-Zn/HA composites were significantly affected by the HA content. Composites with a low HA content showed increased porosity, improved mechanical strength, and enhanced corrosion resistance after ball milling and cold pressing. These results underscore the importance of optimizing the HA content in Mg-Zn/HA composites for bone implants. Based on our findings, PM Mg-Zn/HA composites with a moderate HA content demonstrate the most promising characteristics as bone implants. The insights gained from this work contribute to the advancement of bone implant materials and hold great potential for enhancing orthopedic surgery outcomes.

Recent advances on innovative bioactive glass-hydroxyapatite composites for bone tissue applications: Processing, mechanical properties, and biological performance

New Hydroxyapatite-Bioactive Glass composites, xHA-(1-x)BG (x = 25, 50, and 75 wt %), are developed using HA and BGMS10 glass powders co-milled up to 2 h prior to Spark Plasma Sintering (SPS). Ball milling (BM) promoted the consolidation of HA-rich powders, whereas hindered the densification of 25HA-75BG samples. HA crystallite size is reduced from > 200 nm (unmilled) to 60 (x = 25 %) or 88 nm (x = 75 %) when using 2 h milled mixtures. Glass crystallization occurred in 75HA-25BG samples processed by SPS at 950 °C: a negligeable effect in the amount of the residual amorphous phase (12.3–13.3 wt %) is produced by BM, while changes are observed in the relative content of crystalline phases, with SiO2 increases from 8.5 to 13.1 wt %, whereas α- and β-CaSiO3 correspondingly decrease. Superior Young’s modulus and Vickers hardness (130 GPa and 726, respectively) are obtained in HA rich products. Biological tests evidenced that the milling treatment does not determine negative consequences on cells viability.

PREPARATION AND CHARACTERIZATION OF HYDROXYAPATITE BY CHEMICAL TREATMENT

Hydroxyapatite powder (HA) was prepared using the chemical precipitation method using diammonium hydrogen phosphate and calcium nitrate tetrahydrate as the starting materials. The solution was kept stirring for 24hrs at room temperature, white precipitates were dried and calcined at 1000ºC and 1200ºC for 4hrs. The powder sample was characterized by scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR), X-ray diffraction (XRD), Elemental dispersive X-ray (EDX). The results showed that obtained HA powders were greatly influenced by synthetic conditions. SEM shows the morphology of crystals structure, large pores sizes were observed at 50µm and 100µm. The FTIR shows the presence of CO32- at 1390 cm-1 and 1384 cm-1 which may be due to the adsorption of atmospheric CO2 on the surface of HA. PO42- was observed at 1046 cm-1 and 1092 cm-1. The EDX shows the presence of C, O, Na, Mg, Al, P, Ca. The histogram of EDX revealed oxygen carbon, phosphorus, and calcium as the major elements, sodium, magnesium, and aluminum were also present.

Characterization of AZ31/HA Biodegradable Metal Matrix Composites Manufactured by Rapid Microwave Sintering

This study reports the development of magnesium alloy/hydroxyapatite-based biodegradable metal matrix composites (BMMCs) through rapid microwave sintering. Magnesium alloy (AZ31) and hydroxyapatite powder were used in four compositions 0, 10, 15 and 20% by weight. Developed BMMCs were characterized to evaluate physical, microstructural, mechanical and biodegradation characteristics. XRD results show Mg and HA as major phases and MgO as a minor phase. SEM results correlate with the XRD findings by identifying the presence of Mg, HA and MgO. The addition of HA powder particles reduced density and increased the microhardness of BMMCs. The compressive strength and Young's modulus increased with increasing HA up to 15 wt.%. AZ31-15HA exhibited the highest corrosion resistance and lowest relative weight loss in the immersion test for 24 h and weight gain after 72 and 168 h due to the deposition of Mg(OH)2 and Ca(OH)2 layers at the sample surface. XRD analysis of the AZ31-15HA sintered sample after an immersion test was carried out and these results revealed the presence of new phases Mg(OH)2 and Ca(OH)2 that could be the reason for enhancing the corrosion resistance. SEM elemental mapping result also confirmed the formation of Mg(OH)2 and Ca(OH)2 at the sample surface, which acted as protective layers and prevented the sample from further corrosion. It showed that the elements were uniformly distributed over the sample surface. In addition, these microwave-sintered BMMCs showed similar properties to the human cortical bone and help bone growth by depositing apatite layers at the surface of the sample. Furthermore, this apatite layer can enhance osteoblast formation due to the porous structure type, which was observed in the BMMCs. Therefore, it is indicative that developed BMMCs can be an artificial biodegradable composite for orthopedic applications.

In situ precipitated hydroxyapatite-chitosan composite loaded with ciprofloxacin: Formulation, mechanical, in vitro antibiotic uptake, release, and antibacterial properties

Three-dimensional hydroxyapatite-chitosan (HA-CS) composites loaded with ciprofloxacin antibiotic (HA–CS–CIP) were formulated using the in situ and the solid-liquid method coupled with the freeze-drying process. The interaction of the HA-CS composite powder and ciprofloxacin antibiotic (CIP) was investigated by batch adsorption essays. The kinetic and the isotherm data were fitted well to the pseudo-second-order and Freundlich models, respectively. The compressive strength of the HA-CS composite was increased by 7-fold and 10-fold when using respectively 15 wt% and 30 wt% of the polymer compared to the HA-CS5 formulation (3.6 ± 0.7 MPa) made only from HA powder and CS gel (5 wt%). However, this parameter decreased from 36.8 ± 8.5 MPa down to 20.5 ± 4.7 MPa when the antibiotic content increased from 0 up to 9 wt%, respectively. The in vitro release results showed a sustained and controlled CIP release for up to 10 days. The release data fitting and modeling indicate that the process follows a Fickian diffusion mechanism. Also, the formulated composite revealed an antibacterial effect against Staphylococcus aureus and Escherichia coli bacteria. The developed composite may be a promising candidate for bone substitution and as an antibiotic local delivery system for the treatment of orthopedic implant-associated infections.

Mechanical Properties of Hydroxyapatite Ceramic Prepared from Micropowder and Nanopowder

In this work, hydroxyapatite ceramics were prepared from hydroxyapatite micropowder and nanopowder. The hydroxyapatite nanopowder was obtained from natural buffalo bone by using a high speed vibro-milling machine for 2 hour. The green compacted pellets of all HA powders were subsequently sintered at 1200, 1250, 1300 and 1350°C for 3 hour and then the physical and mechanical characterizations as well as microstructural evaluation have been carried out. It was found that the optimum sintering temperature were 1250°C by fabricated from nanopowder which gave the HA nanoceramic with the maximum bending strength of 78.6±2.6 MPa. This is about 200% higher than that of the sample which fabricated from HA micropowder.

The effect of hydroxyapatite filler on biodegradable poly(sorbitol sebacate malate) composites

AbstractBiodegradable poly(sorbitol sebacate malate)/hydroxyapatite (PSSM/HA) composites were successfully synthesized through one step catalyst‐free polycondensation of sorbitol, sebacic acid, malic acid, and HA powder as filler for the composites. The addition of HA improved the tensile modulus and strength of the materials compared with pure PSSM. The elongation at break of the composites was slightly reduced with increasing HA content. The PSSM and HA showed good compatibility, which was evidenced by good distributions of HA particles in the matrix. In vitro degradation and cytotoxicity tests were conducted to investigate the degradation profile and the toxicity of the biocomposites, respectively. The biocomposites also degraded nearly up to ~50% after 6 weeks of study and the degradation products were shown non‐cytotoxic. It was observed that the biocomposites were soft, elastic with Young's modulus and also biodegradable which is potential to be used in biomedical fields such as tissue engineering application.

Preparation of a hydroxyapatite–silver gradient bioactive ceramic coating with porous structure by laser cladding: A study of in vitro bioactivity

Porous coatings play a critical role in osseointegration between the artificial joint implant and host bone. Herein, a previously developed hydroxyapatite–silver (HA-Ag) gradient bioactive ceramic coating with a three-layer structure is further improved. Through laser cladding, a bioactive porous ceramic coating was prepared by adding carboxyl multi-walled carbon nanotubes (CMWCNTs) to HA powder. In this study, the effects of the added amount of CMWCNTs on the pore size, porosity, and active substance content were investigated. The results showed that the porous structure of the bioactive surface layer was gradually changed from the round hole shape to the reticular porous shape when the addition amount of CMWCNTs was increased from 5 wt % to 20 wt %, and the most appropriate amount of CMWCNTs was 10 wt %. In addition, the biocompatibility of the porous ceramic coating, as well as its effect on the alkaline phosphatase (ALP) activity of osteoblasts, were evaluated in vitro. Simulated body fluid (SBF) soaking tests were applied to determine the changes in ion concentration and calculate the concentration quotient and transfer free energy of Ca2+ and PO43− during the soaking period in SBF. The effects of the porous ceramic coating on the nucleation and growth of HA were also validated. The results showed that the preparation of the gradient porous ceramic coating was beneficial to the nucleation and growth of apatite, further improving the bioactivity of the coating to achieve osseointegration between the artificial joint implant and host bone.

Numerical modeling and experimental verification of the composite material of PA12/HA with parameterized random distribution in selective laser sintering

PurposeThe purpose of this study is to establish a finite element (FE) model with the random distribution of the Nylon12/hydroxyapatite (PA12/HA) composite material in selective laser sintering (SLS) process for considering the material anisotropy, which aims to obtain the law of temperature and stress changes in PA12/HA sintering.Design/methodology/approachBy using python script in Abaqus, the FE model is established in which the two materials are randomly distributed and are assigned to their intrinsic temperature-dependent physical parameters. Molten pool sizes at various process parameters were evaluated in terms of numerical simulation and scanning electron microscope analysis, identifying a good agreement between them. Evaluation of temperature and stress distribution under the condition of different HA contents was also conducted.FindingsIt shows that the uneven distribution and quantity of HA powder play a vital role in stress concentration and temperature increase. Additionally, the influence of HA addition on the mechanical performance of SLS-fabricated parts shows that it is conducive to improve compressive strength when the HA ratio is less than 5% because an excess of HA powder tends to bring about a certain amount of microspores resulting in a decrease in part density.Originality/valueThe FE model of the PA12/HA composite material with parameterized random distribution in SLS can be applied in other similar additive manufacturing technologies. It provides a feasible guideline for the numerical analysis of properties of composite materials.

Preparation and characterization of biocomposites based on chitosan and biomimetic hydroxyapatite derived from natural phosphate rocks

Highly porous chitosan/hydroxyapatite (CS/HA) biocomposite scaffolds were prepared using the freeze-gelation method. A starting biomimetic HA powder was synthesized by a wet precipitation method using an abundant natural phosphate (NP) ore as raw material. Then, CS/HA scaffolds with different weight ratios (100/0; 90/10; 80/20; 70/30) have been prepared. The used powders and synthesized scaffolds were characterized by XRF, ICP-MS, FTIR, TG-DSC, XRD, SEM, and cell viability. The results showed that the precipitated raw powder was mainly composed of HA and amorphous calcium phosphate (ACP) with some traces of Mg2+, SiO42−, Sr2+, Na+ and Fe2+ ions which were usually found in such mineral NP precursors. The heat treatment of the raw powder at more than 750 °C leads to the formation of Mg-substituted β-tricalcium phosphate (β-TCMP). Moreover, the culture of human embryonic kidney cells indicated the non-cytotoxicity of the as-prepared powder. On the other hand, the elaborated CS/HA scaffolds exhibited a highly porous structure with well-interconnected pores and homogeneously dispersed HA particles. The measurement of swelling capacity under physiological conditions revealed that the addition of HA to the CS matrix effectively decreased the swelling percentage. The obtained results suggest that the elaborated CS/HA composites may have effective potential as biocompatible scaffolding materials for bone tissue engineering.

Fabrication of novel bio-adsorbent and its application for the removal of Cu(II) from aqueous solution.

As eco-friendly adsorption material, hydroxyapatite (Ca5(PO4)3OH, HA) has been extensively applied to the removal of heavy metal ions. However, separating and recovering of HA powder after the adsorption process limits their application. Alginate-based composite beads (HCA) encapsulated with HA and cellulose were designed to remove Cu(II) from aqueous solution. Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS) were used for characteristic analysis. An extensive discussion in terms of HCA adsorption capacity, effect of various Cu(II) concentration, and analysis of the involved mechanisms of Cu(II) removal on the biosorption. HCA beads showed that the maximum adsorption capacity for Cu(II) of 64.14mg/g at pH = 5 with 8h contact time. The Langmuir adsorption isotherm and second-order kinetic model gave the closest fit. HCA beads display good regeneration ability after four cycles and offer potentiality for practical application.

Investigation of microstructure, crystallographic texture, and mechanical behavior of magnesium-based nanocomposite fabricated via multi-pass FSP for biomedical applications

In this work, the microstructure, crystallographic texture, hardness, and tensile behavior of AZ91/HA bio-nano composite manufactured by multi-pass friction stir processing (FSP) were investigated. With increasing the number of FSP passes, the average size of grains is reduced. The processed AZ91 and AZ91/HA nanocomposite after the third pass had the lowest grain size (4.5 and 2.6 μm, respectively). Also, the average grain size of composites was smaller than that of monolithic samples at the same pass number. The results showed that particle distribution in the AZ91/HA nanocomposite is significantly affected by the number of passes. The increment of the pass number led to a more uniform dispersion of HA nanoparticles in the matrix due to more plastic flow of materials. With increasing the pass number to three, the accumulated strain increased to 0.726 (monolithic) and 0.623 (composite) due to repeating mechanical stirring. There was a texture transition ({101‾1} to {0002}) via performing only one pass of FSP. Suppression of grain rotation by HA nanoparticles maintained the intensity of {101‾1} texture as a corrosion-resistant orientation after the third pass. With increasing the pass number of FSP, the hardness and strength of samples increased due to the grain size reduction and the more uniform dispersion of HA powder. The composite sample after the third pass exhibited the highest hardness of 117.0 HV and ultimate tensile strength of 306.6 MPa. The failure mode of processed samples was ductile. There were smaller dimples on the fracture surface of the composite samples due to their lower grain size and also the presence of HA nanoparticles. Considering the obtained results, the nanocomposite after the third pass can be a good load-bearing implant for biomedical applications.

Investigation of machining and modified surface features of 316L steel through novel hybrid of HA/CNT added-EDM process

Hydroxyapatite powder (HAp) mixed-EDM process causes surface defects including a high roughness, crack and a thick recast layer attributing a low wettability and amorphous alloys as well as a low material erosion rate (MER) while processing the metallic biomaterials. To mitigate these occurrences, many measures have been conducted. This research aims to investigate the feasibility of hybrid HA and carbon nanotubes (CNT) powders mixed EDM process for processing 316L steel. This study also aims to explore the impacts of CNT and the associated variables on machining and surface characteristics of 316L steel. To ameliorate the machining and surface responses, a high electrically and thermally conductive CNT particles have been added in the HAp suspended mineral oil. To address the set objectives, several characterizations techniques including profilometer, goniometer, energy dispersive X-ray (EDX), X-ray diffraction (XRD), and scanning-electron microscope (SEM) have been carried out. In this study, the multiple additives (HAp and CNT) mixed-EDM process has been successfully introduced. Addition of the CNT in the HAp mixed mineral oil improves MER to 26.47 mg/min and declines SR to 3.16 μm. A thin uniform recast layer of 12.4 μm attributing cracks free surface and a high hydrophilic in nature having contact angle of 35° has been obtained in this study. Elemental composition analysis reveals a high content of Ca, P, O and C in the recast layer formed. The oxides, carbides, and CNT reinforced Ca-P based oxides with both crystalline and amorphous phases have been achieved. In this research work, a novel and effective method for processing the biomedical devices made of 316L steel has been proposed.

Synthesis of highly porous iron-doped carbonated hydroxyapatite spheres for efficient adsorption of carmine dyes

Highly porous Fe-doped carbonate hydroxyapatite spheres (Fe-CHAs) were synthesized by two-step hydrothermal method and characterized by SEM, XRD and FTIR. The synthesized Fe-CHAs were confirmed as B-type substituted CHAs. Fe-CHAs with desirable hierarchical mesoporous structure exhibited BET surface area of 93.8 m2/g, pore diameter of 37.4 nm, and pore volume of 0.523 cm3/g. Carmine dye was chosen as model organic dye to investigate the adsorption properties of Fe-CHAs. The maximum adsorption capacity of Fe-CHAs was 55.89 mg/g, which was about seven times as much as that of HA powder. Adsorption kinetics carmine dye molecules onto Fe-CHAs followed the second-order kinetic equation and Langmuir model, indicating that adsorption of carmine dye molecules onto Fe-CHAs was mainly monolayer chemical adsorption. Experimental results show that these highly porous Fe-CHAs could be a potential efficient adsorption material for removing organic dyes in industrial wastewater.