• Proceedings of the KOSOMBE Conference
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• v.1996 no.05
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• pp.221-222
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• 1996

In order to prepare the porous hydroxyapatite (HA) ceramics with different porosity, interconnectivity, mechanical properties, surface chemistry and tissue response, several methods have been developed. Of the different forms of Porous HA ceramics which were prepared by various methods, only the coralline HA has undergone major clinical applications in orthopaedic, maxillofacial and ophthalmic surgery. In this study, totally synthetic macroporous HA ceramics with various pore size distribution were prepared. It is shown that the new reticulate HA ceramics, comprised of interconnected voids surmunded by a web of ceramic, have a morphology which mimics that of human trabecular bone.

• Journal of Biomedical Engineering Research
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• v.19 no.5
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• pp.449-454
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• 1998

It is well known that new tissue or blood vessel is grown into a porous calcium phosphate ceramics used as a bone graft substitute due to their excellent biocompatibility. In this study, the most chemically stable porous $\beta$-crystalline form in various forms of calcium metaphosphate, Ca(PO$_3$)$_2$is prepared by the controlled thermolysis of monocalcium phosphate, Ca(H$_2$PO$_4$)$_2$.The diameter of cylindrical pores formed during cooling was controlled by a holding time at the melting point of a monocalcium phosphate and by the change of a crystallization temperature, to obtain the most appropriate size (about 200$\mu$m) of pores for the application of bone substitutes and matricuts. It was observed that the increasing holding time at the melting point of monocalcium phosphate results in the decreases of cylindrical pore sizes.

• Journal of the Korean Ceramic Society
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• v.35 no.3
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• pp.209-218
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• 1998

Ca-deficiency frequently observed in the hydroxyapatite powders prepared by precipitation which is known to be deleterious for its application to biomaterials was prevented by the technique developed in this study. In addition the prepared powder has been revealed to be quite active that full density is achieved at temperatures as low as 100$0^{\circ}C$ Instead of using N2 air was chosen as the processing atmosphere during the precipitation and aging of hydroxyapatite. {{{{ {CO }`_{3 } ^{2- } }} ions from the processing atmosphere(air) substitute partly for {{{{ {PO }`_{4 } ^{3- } }} ions in the hydroxyapatite and its content can be controlled by pH of the solution where the pre-cipitation reaction occurs.

• Journal of the Korean Ceramic Society
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• v.23 no.3
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• pp.67-77
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• 1986

various properties and manufacturing conditions were investigated in order to synthesize the glass-ceramics of $CaO-P_2O_5$ system for bioceramics. Compositions of easy unidirectional crystallization were between 47.5 and 50, 0mol% CaO For the glass rods prepared by pulling them to about 3 times the original rod length unidirectional crystallization was easier than original glass rods. These samples were crystallized in the axial direction at 15${\mu}{\textrm}{m}$/min in an electric furnace with a temperature gradient of about 3$0^{\circ}C$/cm at 57$0^{\circ}C$. Bending strengths of surface and unidirectionally crystallized samples were investigated with various CaO/$P_2O_5$ molar ratios. The bending strengths of unidirectionally crystallized samples were larger than those of surface -crystallized samples and the value of 47.5CaO.52.5 $P_2O_5$ was 1650kg/$cm^2$. XRD patterns showed that major phase is $\beta$-Ca(PO3) with minor phase 2CaO.$P_2O_5$ Relative crystal-linity of surface-crystallized sample was inversely propertional to the bending strenth. SEM of fracture surface of unidirectionally crystallized samples revealed an unidirectionally aligned structures.

• Journal of the Korean Society for Precision Engineering
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• v.26 no.9
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• pp.121-126
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• 2009

Stainless steel 316L (STS 316L) is widely used as a material of biopsy needle. However it has a side effect that tissue can be damaged by electrochemical operation between tissue and STS 316L. Many studies have been made on the ceramic coating of biopsy needle to reduce the side effect. In this study, STS 316L was coated with three bioceramics, $Al_2O_3$, $SiO_2$ and $ZrO_2$ using a RF magnetron sputtering method. The effects of ceramic coating on the electrical conductivity and coating strength of ceramic-coated STS 316L were investigated. The results showed that the electrical conductivity of ceramic-coated STS 316L was much lower than that of uncoated STS 316L. The coating strength of $ZrO_2$-coated STS 316L was 30% and 70% higher, respectively than those of $Al_2O_3$-coated STS 316L and $SiO_2_3$-coated STS 316L.

• Journal of Biomedical Engineering Research
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• v.43 no.4
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• pp.219-229
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• 2022

In this study, we propose a miniaturized micro-ceramic heater device. After screen-printing a silver paste between pre-sintered two aluminum oxide plates to integrate a heating circuit, the device was fabricated through a low-temperature sintering process. In order to configure the optimal heating circuit integration condition, the output current evaluation and heating test were performed according to the number of screen prints of the silver paste at various voltages. A silver paste-based heating circuit printed with a line width of 200 ㎛ and a thickness of 60 ㎛ was successfully integrated on a pre-sintered alumina substrate through a low-temperature sintering process. In the case of the 5 times printed device, the thermal response showed a response rate of 18.19 ℃/sec. To demonstrate feasibility of the proposed device in the medical field, such as bio-tissue suturing and hemostasis, a voltage was applied to pig tissue in the device to test tissue change due to heat generated from the device. These results show the possibility that the proposed small ceramic heater could be used in the medical field based on its excellent temperature response.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.32 no.5
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• pp.183-190
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• 2022

Diopside (CaMgSi₂O₆) is known to have high bioactivity as well as excellent mechanical properties. In this study, we tried to improve the bioactivity of zirconia ceramics by surface coating of diopside and its bioactivity was investigated through an in vitro test. Surface coating on zirconia substrate was prepared by sol-gel method using a diopside sol which was prepared by dissolving Ca(NO₃)₂·4H₂O, MgCl₂·6H₂O and Si(OC₂H₅)₄ in ethanol with a fixed molar ratio and then hydrolysis. To examine the bioactivity of diopside coating, we examined the surface dissolution and the precipitation of new hydroxyapatite particles through in vitro test in SBF (Simulated Body Fluid) solution. Dense and thick diopside coating layers could be fabricated on zirconia substrate by sol-gel method. Also, we confirmed that they contained high bioactivity from the in vitro test, indicated the precipitation of hydroxyapatite particles after the 14 days immersion in SBF solution. In addition, we checked that the bioactivity of diopside coated layers was dependent on the repeated coating cycle and coating thickness.

• Journal of the Korean Ceramic Society
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• v.39 no.5
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• pp.490-497
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• 2002

Sintering property, mechanical property and bioactivity of $CaO-SiO_2-B_2O_3$ glass-ceramics were investigated. This glass-ceramics was sintered at 750-830${\circ}$ and showed nearly pore-free microstructure. The glass-ceramics consisted of three phases, i.e. monclinic-wollastonite, calcium borate and borosilicate glass matrix. The mechanical strength was higher than that of other bioactive ceramics, especially compressive strength(2813 MPa) and fracture toughness($3.12 MPa{\cdot}m^{1/2}$). Bioactivity of the glass-ceramics depends on amount of $CaB_2O_4$ and borosilicate glass matrix. It might be likely that more soluble $CaB_2O_4$ raises supersaturation of Ca ion in SBF solution and borosilicate glass forms Si-OH group that presents nucleation site of hydroxycarbonate apatite(HCA) layer. So, glassceramics of more $CaB_2O_4$ and borosilicate glass showed better bioactivity.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.3
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• pp.139-146
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• 2012

Natural hydroxyapatite powder was obtained from the calcination of bovine bones and its porous compacts were fabricated by pressureless sintering at 1100 and $1200^{\circ}C$ for 1h. To evaluate and compare their biocompatibility with porosity, we investigated the support of osteoblast cells growth and cytotoxicity using the MG-63 cell line model in vitro. Sintered hydroxyapatite ceramics have a porous microstructure with a relative density of 65 % at $1100^{\circ}C$ and 82 % at $1200^{\circ}C$. Cells adherence to the surface of hydroxyapatite ceramics was observed in a day after the cell culture, and the spreading of cytoplasm around the nucleus was shown after 3 day cell culture. Most of cells were extended to the surface of hydroxyapatite through the wide area. Cell viability was nearly the same till 3 days culturing. But the rate of cell growth is higher in the specimen sintered at $1100^{\circ}C$ than that of $1200^{\circ}C$. It indicates that the porosity is an important factor to enhance the cell viability in the porous hydroxyapatite ceramics derived from bovine bones.

• Korean Journal of Materials Research
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• v.22 no.6
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• pp.285-291
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• 2012

Hydroxyapatite (HA) is well known as a biocompatible and bioactive material. HA has been practically applied as bone graft materials in a range of medical and dental fields. In this study, two types of dense hydroxyapatite ceramics were prepared from natural bones and synthetic materials. The biocompatibility of HA ceramics for supporting osteoblast cell growth and cytotoxicity using an in vitro MG-63 cell line model were respectively evaluated. Artificial hydroxyapatite shows relative density of 93% with 1-2 ${\mu}m$ after sintering, but a hydroxyapatite compact derived from bovine bone has low sintered density of 85% with a small content of MgO. Irrespective of the starting raw materials, both types of sintered hydroxyapatite displayed similar biocompatibility in the tests. FE-SEM observations showed that most MG-63 cells had a stellar shape and formed an intercellular matrix containing fibers on sintered HA. The cells were well attached and grown over the HA surface, indicating that there was no toxicity.