本研究以溶凝膠法合成氫氧基磷灰石(HA)；前驅物為含四結晶水的硝酸鈣及三乙基正磷酸酯(TEP)溶解於2-甲氧基乙醇之溶液。在第一部份中，凝膠在煆燒到600oC後，X-光粉末繞射(XRD)圖譜顯示快速乾燥所得之粉體含有HA及明顯的氧化鈣(CaO)。緩慢乾燥後凝膠經熱重損失分析顯示煆燒過程為二步驟式的重量損失。600oC煆燒後的粉體含有主相HA及微量的CaO雜相。這些微量的CaO可用去離子水清洗並過濾去除之。
在第二部份中，由前驅物熟化及乾燥處理後可發現TEP的水解反應及其產物。從固態磷-31核磁共振及XRD圖譜可發現，前驅物煆燒到250oC時為凝膠相，在350oC時轉變為玻璃態磷酸酯，在600oC時為生成HA。

第三部份對乾燥之前驅物施以100~600 oC/min的快速煆燒(RTC)及1.67 oC/min 的傳統高溫爐煆燒(CFC)。XRD圖譜顯示施以RTC時HA結晶化溫度在350oC，遠低於CFC的600oC。搭配快速裂解-氣相層析儀串接質譜儀(Pyrolytic-GC/MS)，煆燒模型得以建立；在較低的煆燒溫度時，凝膠裡有機物質受到快速加熱(RTC)而快速分解。在表面形成孔隙型態，在凝膠網絡裡微區有機物質崩解。因此，這些無機物質緊密地碰在一起使HA孕育成核。但在慢速煆燒(CFC)下分解的有機碳化物卻阻礙了無機物的接觸。因此，HA在600oC下才能生成。

在第四部分中，製備HA塗層於鈦-六鋁-四釩合金基材。對每一塗層以RTC煆燒至400oC，連續製備5層後再以RTC於600oC煆燒一次。XRD圖譜顯示HA已形成。以X-光光電子能譜儀探測400oC煆燒後之塗層表面，結果顯示只有部分的磷酸鈣相，因為殘餘有機物質會阻礙該相之形成。600oC煆燒後，只有發現磷酸鈣相。五層厚的HA鍍層接著強度為60MPa。以SEM觀察分別經過400oC及600oC RTC煆燒後的鍍層表面，在較厚的區域發現孔隙狀結構，原因是較多的前驅物受到快速加熱而分解。

The present study aims at a sol-gel processing of hydroxyapatite (HA) using precursors of calcium nitrate tetrahydrate and triethyl phosphate dissolved in 2-methoxy ethanol. Firstly, for the aged and slow-dried precursor, XRD pattern showed major peaks of HA and a very weak CaO peak. This minor CaO can be easily and completely washed out just by using distilled water. Secondly, during aging and drying, 1H NMR spectra showed hydrolyzed species: PO(OEt)2(OH) and PO(OEt)(OH)2. In solid-state MAS 31P NMR spectra, dried gels calcined at 250oC, 350oC and 600oC showed a conversion from gel to glassy phosphate, then HA ceramic.
Thirdly, the dried gels were calcined by a rapid-thermal-calcine (RTC) heating (100~600 oC/min) and a conventional-furnace-calcine (CFC) heating (1.67 oC/min), respectively. The onset temperature of HA crystallization is lower in RTC, 350oC, as compared to 600oC in CFC, revealed by XRD analyses. Pyrolytic-GC/MS results combined with previous ones lead to models that RTC can catastrophically remove organic portion of the gel networks, leading to a porous surface morphology and a collapse of gel networks at local areas, so that HA crystallite nucleation is facilitated due to intimate contacts among inorganic species at lower temperatures. On the other hand, slow evolution of organics during CFC leads to carbonaceous residues that isolate the inorganic species and inhibit nucleation of HA crystallites until at a higher temperature.

Finally, HA coatings were deposited on Ti-6Al-4V substrates and subjected to a pre-calcined at 400oC. After five repetitions of coating procedures the coatings were then RTC at 600oC. The formation of HA was confirmed by XRD analysis. The residual organics, as revealed by XPS spectra of a coating calcined at 400oC, might retard the formation of calcium phosphate phase, thus only small amount of calcium phosphate phase is present. After calcining at 600oC, calcium phosphate phase is the only one identifiable in XPS spectra. The adhesive strength of the five-layer coating on the substrate is around 60 MPa.

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