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1 – 10 of 44
Article
Publication date: 10 June 2014

Teodora Marcu, Cinzia Menapace, Luca Girardini, Dan Leordean and Catalin Popa

The purpose of this paper was to obtain by means of selective laser melting and then characterize biocomposites of medical-grade Ti6Al7Nb with hydroxyapatite (2 and 5 vol.%) and…

Abstract

Purpose

The purpose of this paper was to obtain by means of selective laser melting and then characterize biocomposites of medical-grade Ti6Al7Nb with hydroxyapatite (2 and 5 vol.%) and without hydroxyapatite, as reference.

Design/methodology/approach

Rectangular samples were manufactured with the same scanning strategy; the laser power was between 50 W and 200 W. Processed samples were analysed by means of optical microscopy, scanning electron microscopy and microhardness.

Findings

The results showed that despite the very short processing times, hydroxyapatite decomposed and interacted with the base Ti6Al7Nb material. The decomposition degree was found to depend on the applied laser power. From the porosity and bulk microstructure point of view, the most appropriate materials for the purposed medical applications were Ti6Al7Nb with hydroxyapatite processed with a laser power of 50 W.

Originality/value

The originality of the present work consists in the study of the behaviour and interaction of hydroxyapatite additive with the Ti6Al7Nb base powder under selective laser melting conditions, as depending on the applied laser power.

Details

Rapid Prototyping Journal, vol. 20 no. 4
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 27 November 2018

Sarbjit Kaur, Niraj Bala and Charu Khosla

The biomaterials are natural or synthetic materials used to improve quality of life either by replacing tissue/organ or assisting their function in medical field. The purpose of…

248

Abstract

Purpose

The biomaterials are natural or synthetic materials used to improve quality of life either by replacing tissue/organ or assisting their function in medical field. The purpose of the study is to analyze the hydroxyapatite (HAP), HAP-TiO2 (25 percent) composite coatings deposited on 316 LSS by High Velocity Flame Spray (HVFS) technique.

Design/methodology/approach

The coatings exhibit almost uniform and dense microstructure with porosity (HAP = 0.153 and HAP-TiO2 composite = 0.138). Electrochemical corrosion testing was done on the uncoated and coated specimens in Ringer solution (SBF). As-sprayed coatings were characterized by XRD, SEM/EDS and cross-sectional X-ray mapping techniques before and after dipping in Ringer solution. Microhardness of composite coating (568.8 MPa) was found to be higher than HAP coating (353 MPa).

Findings

During investigations, it was observed that the corrosion resistance of steel was found to have increased after the deposition of HAP and HAP-TiO2 composite coatings. Thus, coatings serve as an effective diffusion barrier to prohibit the diffusion of ions from the SBF into the substrate. Composite coatings have been found to be more corrosion resistant as compared to HAP coating in the simulated body fluid.

Research limitations/implications

It has been concluded that corrosion resistance of HAP as well as composite coating is because of the desirable microstructural changes such as low porosity high microhardness and flat splat structures in coatings as compared to bare specimen.

Practical implications

This study is useful in the selection of biomedical implants.

Social implications

This study is useful in the field of biomaterials.

Originality/value

No reported literature on corrosion behavior of HAP+ 25%- TiO2 has been noted till now using flame spray technique. The main focus of the study is to investigate the HAP as well as composite coatings for biomedical applications.

Details

Anti-Corrosion Methods and Materials, vol. 66 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 1 October 2003

F. Hanna and Z.A. Hamid

This work concerns the electrodeposition of highly pure brushite (CaHPO4·2H2O) on titanium alloy substrates and the transformation of the brushite to hydroxyapatite (HAp) Ca10(PO4

Abstract

This work concerns the electrodeposition of highly pure brushite (CaHPO4·2H2O) on titanium alloy substrates and the transformation of the brushite to hydroxyapatite (HAp) Ca10(PO4)6(OH)2 as a coating for orthopaedic implants. Thus, the electrodeposition of electrolyte containing calcium nitrate and ammonium hydrogen phosphate was carried out. The influences of the substrate surface treatment, the electroplating conditions (bath composition, current density, pH value and temperature) and the hydrothermal post treatment conditions on the deposition rate, the throwing power, the adhesion, the morphology and the structure of the coating were evaluated. High adhesion bond strength (around 23 mPa) was achieved on a rough clean substrate, which is slightly higher than plasma sprayed HAp coating on titanium alloy.

Details

Pigment & Resin Technology, vol. 32 no. 5
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 12 August 2014

I. Pires, B. Gouveia, J. Rodrigues and R. Fonte

The purpose of this study is to characterize sintered hydroxyapatite (HA) samples produced by three-dimensional printing (3DP). This study is part of a project concerned with the…

Abstract

Purpose

The purpose of this study is to characterize sintered hydroxyapatite (HA) samples produced by three-dimensional printing (3DP). This study is part of a project concerned with the fabrication of calcium phosphates implants by 3DP. However, before considering a more complex structure, like scaffolds or implants, a thorough knowledge of the role played by the sintering temperature on physical and mechanical the properties of porous HA is necessary.

Design/methodology/approach

The characteristics of sintered HA samples have been analyzed by means of x-ray diffraction, scanning electron microscope (SEM) and uniaxial compression tests. The 3DP parameters used to produce the HA samples were those who led to higher accuracy and mechanical stability.

Findings

Sintering temperature and powder morphology are critical factors influencing densification behavior, porosity, phase stability, mechanical strength and tangent modulus of the HA samples produced by 3DP. This study allowed us to conclude about the 3DP parameters to be used to produce porous HA specimens with the required integrity and dimensional accuracy, and the optimal post-processing sintering temperature which led to the best results in terms of porosity, microstructure, phase stability of HA and mechanical properties.

Originality/value

This paper provides a method to evaluate the manufacturability of calcium phosphate models produced by 3DP.

Details

Rapid Prototyping Journal, vol. 20 no. 5
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 23 October 2021

Fangfang Sun, Tianze Wang and Yong Yang

Rapid prototyping (RP) technology is widely used in many fields in recent years. Bone tissue engineering (TE) is an interdisciplinary field involving life sciences, engineering…

Abstract

Purpose

Rapid prototyping (RP) technology is widely used in many fields in recent years. Bone tissue engineering (TE) is an interdisciplinary field involving life sciences, engineering and materials science. Hydroxyapatite (HAp) are similar to natural bone and it has been extensively studied due to its excellent biocompatibility and osteoconductivity. This paper aims to review nanoscaled HAp-based scaffolds with high porosity fabricated by various RP methods for bone regeneration.

Design/methodology/approach

The review focused on the fabrication methods of HAp composite scaffolds through RP techniques. The paper summarized the evaluation of these scaffolds on the basis of their biocompatibility and biodegradability through in vitro and in vivo tests. Finally, a summary and perspectives on this active area of research are provided.

Findings

HAp composite scaffold fabricated by RP methods has been widely used in bone TE and it has been deeply studied by researchers during the past two decades. However, its brittleness and difficulty in processing have largely limited its wide application in TE. Therefore, the formability of HAp combined with biocompatible organic materials and fabrication techniques could be effectively enhanced, and it can be used in bone TE applications finally.

Originality/value

This review paper presented a comprehensive study of the various types of HAp composite scaffold fabricated by RP technologies and introduced their potential application in bone TE, as well as future roadmap and perspective.

Details

Rapid Prototyping Journal, vol. 28 no. 3
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 4 January 2019

Wenhao Wang, Rujing Shi, Wei Zhang, Haibin Sun, Xiaolu Ge and Chengfeng Li

The purpose of this paper is to improve the generation efficiency of singlet oxygen of methylene blue molecules through finely controlling their aggregation states in drug…

213

Abstract

Purpose

The purpose of this paper is to improve the generation efficiency of singlet oxygen of methylene blue molecules through finely controlling their aggregation states in drug carriers.

Design/methodology/approach

As a photosensitiser in photodynamic therapy, methylene blue (MB) was loaded on citrate-modified hydroxyapatite (HAp) through an electrostatic interaction and followed by encapsulation of coordination complexes of tannic acid (TA) and Fe(III) ions. Ultraviolet-visible absorption spectrum of the supernatant after incubation of samples was recorded at certain time interval to investigate the release behaviour of MB. Photodynamic activity of MB was determined by the oxidation reaction of uric acid by singlet oxygen generated by MB under illumination.

Findings

Almost all MB molecules were immediately released from HAp-MB, whilst an initial burst release of MB from HAp-MB@TA was followed by a sustainable and pH-sensitised release. In comparison with HAp-MB, photocatalystic reduction of HAp-MB@TA by titanium dioxide hardly occurred under illumination, indicating the stability against reduction to leukomethylene blue in vitro. Generation efficiency of singlet oxygen by MB released from HAp-MB@TA was significantly higher than that from HAp-MB because of the control of TA and Fe(III) ions complexes on molecular structures of released MB.

Originality/value

A facile method was herein demonstrated to optimise the generation efficiency of singlet oxygen by controlling aggregation states of PS molecules and improve PDT efficiency to damage tumour tissues.

Details

Pigment & Resin Technology, vol. 48 no. 2
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 5 June 2020

Kesheng Lin, Jie Liu, Jia-Min Wu, Yunlong Sun, Feng Li, Yan Zhou and Yusheng Shi

The main cause of aseptic inflammation after an in vivo implantation is that Poly(L-lactide) (PLLA) and Poly(D-lactide) have a slower degradation and absorption rate, while…

Abstract

Purpose

The main cause of aseptic inflammation after an in vivo implantation is that Poly(L-lactide) (PLLA) and Poly(D-lactide) have a slower degradation and absorption rate, while Poly(D, L-lactide) (PDLLA) has a much faster degradation rate than PLLA because of its amorphous structure. Also, the hydrolyzate of Hydroxyapatite (HA) is alkaline, which can neutralize local tissue peracid caused by hydrolysis of Polylactic acid.

Design/methodology/approach

In this study, the selective laser sintering (SLS) technique was chosen to prepare bone scaffolds using nano-HA/PDLLA composite microspheres, which were prepared by the solid-in-oil-in-water (S/O/W) method. First, the SLS parameters range of bulk was determined by the result of a single-layer experiment and the optimized parameters were then obtained by the orthogonal experiment. The tensile property, hydrophobicity, biocompatibility, biological toxicity and in vitro degradation of the samples with optimized SLS parameters were characterized.

Findings

As a result, the samples showed a lower tensile strength because of the many holes in their interior, which was conducive to better cell adhesion and nutrient transport. In addition, the samples retained their inherent properties after SLS and the hydrophobicity was improved after adding nano-HA because of the OH group. Furthermore, the samples showed good biocompatibility with the large number of cells adhering to the material through pseudopods and there was no significant difference between the pure PDLLA and 10% HA/PDLLA in terms of biological toxicity. Finally, the degradation rate of the composites could be tailored by the amount of nano-HA.

Originality/value

This study combined the S/O/W and SLS technique and provides a theoretical future basis for the preparation of drug-loaded microsphere scaffolds through SLS using HA/PDLLA composites.

Details

Rapid Prototyping Journal, vol. 26 no. 6
Type: Research Article
ISSN: 1355-2546

Keywords

Article
Publication date: 3 February 2020

Santosh Kumar, Manoj Kumar and Neeru Jindal

This paper aims to consolidate the results of various researchers focusing the different applications, so that this paper could become the torch bearer for the futuristic…

Abstract

Purpose

This paper aims to consolidate the results of various researchers focusing the different applications, so that this paper could become the torch bearer for the futuristic researchers working in the domain of cold gas dynamics spray coating.

Design/methodology/approach

A study on the cold spray coating is presented by summarizing the data present in literature. Important factors such as coating temperature, pressure, coating thickness, particle size, which affect the erosion-corrosion (E-C) resistance, physical and mechanical properties of boiler steel are stated. This paper also addresses the use of cold spray coating and compares it with other different thermal spray processes.

Findings

From the literature review, it was noticed that cold spray technology is best as compare to other thermal spray processes to reduce porosity, increase hardness, adhesion strength and retention in properties of feedstock powders.

Originality/value

Cold spray coating technology has a great potential in almost every field especially in restoration of surfaces, generation of complex surface, biomedical application, resist hot corrosion, wear, oxidation and erosion corrosion.

Details

World Journal of Engineering, vol. 17 no. 1
Type: Research Article
ISSN: 1708-5284

Keywords

Article
Publication date: 8 May 2017

Mimi Azlina Abu Bakar, Siti Norazlini Abd Aziz and Muhammad Hussain Ismail

This paper aims to investigate the vital characteristic of an innovative ceramic injection molding (CIM) process for orthopedic application with controlled porosity and improved…

Abstract

Purpose

This paper aims to investigate the vital characteristic of an innovative ceramic injection molding (CIM) process for orthopedic application with controlled porosity and improved tribological and mechanical properties which were affected by complex tribological interactions, whether lubricated like hip implants and other artificial prostheses. The main objective is to maximize the usage of palm stearin as a single based binder as the function of flow properties during injection molding process.

Design/methodology/approach

The binder used in this present study consists of 100 per cent palm stearin manufactured by Kempas Oil Sdn Bhd and supplied by Vistec Technology Sdn Bhd. The feedstock was prepared by using a Z-blade mixer (Thermo Haake Rheomix OS) and Brabender mixer model R2400. The feedstock prepared was injection molded using a manually operated vertical benchtop machine with an average pressure of about 5-7 bars. The firing step included the temporary holds at intermediate temperatures to burn out organic binders. At this stage, the green molded specimen was de-bound using a single-step wick-debinding method.

Findings

The maximum content of ceramic material is applied to investigate the efficiencies of net formulation that can be achieved by ceramic materials. The longer the viscosity will change with shear rate, the higher the value of n obtained instead. From the slope of the curves obtained in Figure 3, the value of n for the feedstock was determined to be less than 1, which indicates a pseudoplastic behavior and suitability for the molding process. Moreover, high shear sensitivity is important in producing complex and intrinsic specimens which are leading products in the CIM industry.

Originality/value

The feedstock containing HAp powder and palm stearin binder was successfully prepared at very low temperature of 70°C, which promoting a required pseudo-plastic behavior during rheological test. The single binder palm stearin should be optimized in other research works carried out, as palm stearin is most preferred compared to other polymeric materials that provided high energy consumption when subjected to the sintering process. Besides the binder is widely available in Malaysia, low cost and harmless effect during debinding process.

Details

Industrial Lubrication and Tribology, vol. 69 no. 3
Type: Research Article
ISSN: 0036-8792

Keywords

Article
Publication date: 12 January 2010

Li‐zhu Liu, Hong‐jie Ma, Xing‐song Zhu, Yu‐jiang Fan and Zhen‐hao Jin

Polylactide/nano‐silica in situ composites are synthesised and characterised in order to study their mechanical and thermal properties. The purpose of this paper is to study these…

Abstract

Purpose

Polylactide/nano‐silica in situ composites are synthesised and characterised in order to study their mechanical and thermal properties. The purpose of this paper is to study these properties and compare them with the pure polylactide (PLA).

Design/methodology/approach

Polylactide/nano‐silica in situ composites are synthesised from lactide and modified nano‐silica using stannous octoate as a catalyst. The structure and properties of the composites are characterised by gel permeation chromatography (GPC), thermal gravimetric analysis (TGA) and scanning electronic microscopy (SEM).

Findings

The results of SEM showed that nano‐silica and PLA are connected with covalent bonds, and that inorganic phases are dispersed homogeneously in the PLA matrix. The results of TGA indicated that the thermal decomposition temperature rose with the increase of silica content. The tensile strength of the composites is enhanced because of the addition of nano‐inorganic particles into PLA.

Research limitations/implications

Although the preparation process is simplified by a two‐step method, attempts will be made to synthesise the polylactide/nano‐silica composites by a one‐step approach to curtail the preparation cycle.

Practical implications

The composites are expected to be suitable for applications in packaging materials, biomedical and pharmaceutical fields.

Originality/value

Preparation of polylactide/nano‐silica composites is expected to exert the respective advantages of the two ingredients and to produce more practical polymer materials.

Details

Pigment & Resin Technology, vol. 39 no. 1
Type: Research Article
ISSN: 0369-9420

Keywords

1 – 10 of 44