Flash sintering of hydroxyapatite ceramics

Hwang, Changhun; Yun, Jondo

doi:10.1080/21870764.2020.1864899

Cited by 8 publications

(7 citation statements)

References 73 publications

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“…This leads to finer microstructures, higher thermal stability, and subsequently better mechanical properties of CaPO 4 bioceramics. In addition, microwave [301][302][303][304][305][306], spark plasma [69,104,[307][308][309][310][311][312][313][314][315], flash [316,317], and ultrafast high-temperature [318] sintering techniques are alternative methods to the conventional sintering, hot pressing, and hot isostatic pressing. Both alternative methods were found to be time-and energy-efficient densification techniques.…”

Section: Sintering and Firingmentioning

confidence: 99%

“…They can exhibit an optical transmittance of ~66% at a wavelength of 645 nm [425]. The preparation techniques include a hot isostatic pressing [87, 185,187,426], an ambient-pressure sintering [420], a gel casting coupled with a low-temperature sintering [421,424], and a pulse electric current sintering [422], as well as spark plasma [69,[307][308][309][310][311][312][313][314][315] and flash [316,317] sintering techniques. Fully dense, transparent CaPO 4 bioceramics are obtained at temperatures above ~800 • C. Depending on the preparation technique, the transparent bioceramics have a uniform grain size ranging from ~67 nm [87] to ~250 µm [421] and are always pore-free.…”

Section: Possible Transparencymentioning

confidence: 99%

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Calcium Orthophosphate (CaPO4)-Based Bioceramics: Preparation, Properties, and Applications

Dorozhkin¹

2022

Coatings

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Various types of materials have been traditionally used to restore damaged bones. In the late 1960s, a strong interest was raised in studying ceramics as potential bone grafts due to their biomechanical properties. A short time later, such synthetic biomaterials were called bioceramics. Bioceramics can be prepared from diverse inorganic substances, but this review is limited to calcium orthophosphate (CaPO4)-based formulations only, due to its chemical similarity to mammalian bones and teeth. During the past 50 years, there have been a number of important achievements in this field. Namely, after the initial development of bioceramics that was just tolerated in the physiological environment, an emphasis was shifted towards the formulations able to form direct chemical bonds with the adjacent bones. Afterwards, by the structural and compositional controls, it became possible to choose whether the CaPO4-based implants would remain biologically stable once incorporated into the skeletal structure or whether they would be resorbed over time. At the turn of the millennium, a new concept of regenerative bioceramics was developed, and such formulations became an integrated part of the tissue engineering approach. Now, CaPO4-based scaffolds are designed to induce bone formation and vascularization. These scaffolds are usually porous and harbor various biomolecules and/or cells. Therefore, current biomedical applications of CaPO4-based bioceramics include artificial bone grafts, bone augmentations, maxillofacial reconstruction, spinal fusion, and periodontal disease repairs, as well as bone fillers after tumor surgery. Prospective future applications comprise drug delivery and tissue engineering purposes because CaPO4 appear to be promising carriers of growth factors, bioactive peptides, and various types of cells.

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Section: Sintering and Firingmentioning

confidence: 99%

Section: Possible Transparencymentioning

confidence: 99%

Calcium Orthophosphate (CaPO4)-Based Bioceramics: Preparation, Properties, and Applications

Dorozhkin¹

2022

Coatings

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“…Sintering of HA coatings is fundamental because the mechanical performance and the biological behavior of a coating are controlled by processes of particle consolidation and coating structure formation. As shown in [27,28], the main purposes of sintering technology are to save the coating microstructure and phase composition and control coating porosity, grain size, adhesion, and bonding strength. From this viewpoint, the application of Pressureless Sintering technology (in the electric resistance chamber furnaces) in ambient air looks reasonable because of the presence of water vapor in the sintering atmosphere that allows for saving HA Ca 10 (PO 4 ) 6 (OH) 2 phase composition.…”

Section: Coating Sinteringmentioning

confidence: 99%

Microstructure and Properties of Hydroxyapatite Coatings Made by Aerosol Cold Spraying–Sintering Technology

et al. 2022

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Hydroxyapatite is a widely used material used for the bioactivation of an implant’s surface. A promising hydroxyapatite coating approach is the kinetic deposition of powder particles. The possibility of solid-state deposition improvement through the merging of Aerosol Deposition and Low Pressure Cold Spraying techniques is a promising prospect for improving the deposition efficiency and the quality of coatings. The objective of the paper is to study the possibilities of hydroxyapatite coating structure modification through changes in the coating process and post-heat treatment. The novel Aerosol Cold Spraying system joining Low Pressure Cold Spraying and Aerosol Deposition was used for the deposition of coatings. The coating’s post-processing was conducted using two techniques: Spark Plasma Sintering and Pressureless Sintering. The coating’s structure was examined using scanning, transmission, and light microscopy, and X-ray diffraction. Substrate–coating bond strength was assessed using a tensile test. Homogenous buildup using Aerosol Cold Spraying of hydroxyapatite was achieved. Various pores and microcracks were visible in the sprayed coatings. The deposition process and the thermal post-processing did not lead to significant degradation of the hydroxyapatite phase. As a result of the Spark Plasma Sintering and Pressureless Sintering at 800 °C, an increase in tensile adhesion bond strength and crystal size was obtained.

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“…Studies also revealed that sintering in a vacuum was more beneficial than in air. At elevated temperatures, the dehydration of HAp leads to the generation of hydroxyl or hydrogen type defects, leading to an increase in the electric current during FS [ 59 ]. In conventional sintering, a higher temperature initiates the transition of the β phase to the α phase of TCP.…”

Section: Conventional Sinteringmentioning

confidence: 99%

Advances in Sintering Techniques for Calcium Phosphates Ceramics

et al. 2021

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Calcium phosphate (CaP) biomaterials are extensively used to reconstruct bone defects. They resemble a chemical similarity to the inorganic mineral present in bones. Thus, they are termed as the key players in bone regeneration. Sintering is a heat treatment process applied to CaP powder compact or fabricated porous material to impart strength and integrity. Conventional sintering is the simplest sintering technique, but the processing of CaPs at a high temperature for a long time usually leads to the formation of secondary phases due to their thermal instability. Furthermore, it results in excessive grain growth that obstructs the densification process, limiting the application of CaP’s ceramics in bone regeneration. This review focuses on advanced sintering techniques used for the densification of CaPs. These techniques utilize the synergy of temperature with one or more parameters such as external pressure, electromagnetic radiation, electric current, or the incorporation of transient liquid that boosts the mass transfer while lowering the sintering temperature and time.

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Flash sintering of hydroxyapatite ceramics

Cited by 8 publications

References 73 publications

Calcium Orthophosphate (CaPO4)-Based Bioceramics: Preparation, Properties, and Applications

Calcium Orthophosphate (CaPO4)-Based Bioceramics: Preparation, Properties, and Applications

Microstructure and Properties of Hydroxyapatite Coatings Made by Aerosol Cold Spraying–Sintering Technology

Advances in Sintering Techniques for Calcium Phosphates Ceramics

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