一种制备羟基磷灰石生物陶瓷涂层的新方法

On a New Laboratory Method for PreparingHydroxyapatite Bioceramic Coating

一种制备羟基磷灰石生物陶瓷涂层的新方法＊憨勇①黄立业②徐可为③生物医用植入材料是材料科学研究的热点之一。近年来，有关学者利用等离子喷涂、粉浆涂覆与烧结、等压压制与烧结等表面改性技术开展了在金属基体上涂覆羟基磷灰石（简称ＨＡＰ，分子式为Ｃａ１０（ＰＯ４...

Hydroxyapatite (HAP or Ca 10 (PO 4) 6(OH 2)) bioceramic can be coated on metal substrate with either plasma spray, or slurry coating and sintering, or isostatic compression and sintering. But these technologies suffer from thrce defects: (1) high cost of HAP powder, (2) decomposition of HAP under high temperature and (3) lack of uniformity in thickness of coating. Now, in our laboratory, these three defects were greatly reduced through a new prepartion method of HAP coating, in which original coating was first deposited on metal substrate with electrocrystallization and then turned into HAP with hydrothermal treatment. Deposition of original coating on titanium was accomplished with potentiostat. The anode was graphite rod and the cathode was titanium. Suitable water solutions of Ca(NO 3) 2 and NH 4H 2PO 4 were mixed, and pH value of electrolyte was adjusted with NH 3·H 2O. Deposition voltage was 1.3～3 V, temperature was 40～70℃, and deposition time was 1.5 h. The deposited original coating received hydrothermal treatment in autoclave. Treatment parameters were: temperature 140～240℃, pressure 0.6～3.6 MPa, pH value 7～10. XRD indicated that original coating consisted completely of CaHPO 4·2H 2O (see Fig.1). After hydrothermal treatment, coating consisted of both HAP and CaHPO 4·2H 2O(Fig.2), whose percentages were 90.5% and 9.5% respectively. Thus hydrothermal treatment can indeed turn CaHPO 4·2H 2O into HPA. With increasing temperature or increasing pH value of hydrothermal treatment, the transformation into HAP became better and better. A temperature of 240℃ and a pH value of 10 were found to be adequate for 100% transformation into HAP. SEM indicated that coating thickness was greater than 50 μm, that uniformity of thickness was quite good, and that the morphology of crystal grains of such HAP was needlelike, very suitable for implanting into human body for replacement of bone, whose HAP crystal grains are needlelike.