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首页> 外文会议>13th International Symposium on Ceramics in Medicine and the Annual Meeting of the International Society for Ceramics in Medicine 22-26 November 2000 Bologna, Italy >On the Sintering Characteristics of Calcium Polyphosphates
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On the Sintering Characteristics of Calcium Polyphosphates

机译：聚磷酸钙的烧结特性

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摘要

Porous calcium polyphosphates (CPP) have been shown to hold promise for tissue engineered implant applications. However initial attempts to form porous CPP structures for these applications by sintering of powders have demonstrated problems with reproducible formation of porous forms of desired geometry from run to run, even for powders taken from a single production batch. Batch to batch variability further confounds this problem. In this study, melt-derived CPP glass powders of prescribed size ranges were gravity sintered under various conditions of temperature, time and humidity in order to better elucidate the role of each of these parameters in controlling the sintering of these powders. No discernible variability in thermal characteristics was detected for each of the powder batches studied. XRD confirmed the consistent amorphous nature of the powder and the formation of monoclinic beta-CPP with high temperature sintering. Significant sinter neck formation without extensive densification, in addition to insufficient sinter neck development with crystallized powders under similar sintering conditions, indicated that a viscous flow mechanism dominated. Sinter neck formation and disk density also moderately increased with increasing heating rate (approx1-10 deg C/m), though this effect was less obvious with the larger particle size range. The relative insensitivity of disk density to higher sintering temperatures (800-950 deg C) at a fixed ramp rate emphasized the importance of controlling sintering kinetics in the 500-700 deg C range where most of the densification occurs and during which humidity and powder size appear to be influential factors. The results of this study suggest that appropriate selection of sintering conditions can result in the reliable development of adequate porous constructs of desired pore size and crystallographic structure (amorphous or crystalline), ultimately allowing a degree of control over porous CPP degradation characteristics.
机译：多孔聚磷酸钙（CPP）已显示出对组织工程植入物应用的希望。然而，通过粉末的烧结来形成用于这些应用的多孔CPP结构的最初尝试已经证明了即使对于一次生产批次的粉末而言，也从头到尾地可再现地形成期望几何形状的多孔形式的问题。批次间的可变性进一步混淆了这个问题。在这项研究中，在各种温度，时间和湿度条件下，将规定尺寸范围的熔体衍生CPP玻璃粉末进行重力烧结，以便更好地阐明这些参数在控制这些粉末烧结中的作用。对于所研究的每批粉末，均未检测到热特性的明显变化。 XRD证实了粉末的一致无定形性质，并通过高温烧结形成了单斜晶β-CPP。在相似的烧结条件下，除了结晶粉未充分形成烧结颈外，没有大量致密化的大量烧结颈形成也表明，粘性流动机理占主导地位。烧结颈的形成和圆盘密度也随着加热速率（大约1-10℃/ m）的增加而适度增加，尽管这种影响在较大的粒径范围内不太明显。在固定的升温速率下，圆盘密度对较高的烧结温度（800-950摄氏度）相对不敏感，这强调了在大多数致密化发生以及湿度和粉末尺寸处于500-700摄氏度范围内控制烧结动力学的重要性。似乎是影响因素。这项研究的结果表明，适当选择烧结条件可以可靠地开发出具有所需孔径和晶体结构（无定形或晶体）的适当多孔结构，从而最终可以控制多孔CPP的降解特性。

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