Micro-surgical instruments are a new application for mesoscale ceramics formed using the lost mold-rapid infiltration forming (LM-RIF) process. Instrument strength and reliability are the foremost concerns for this sensitive application. It is hypothesized that increasing grain size can improve the damage tolerance of the parts associated with the transformation toughening in the 3Y-TZP material, while retaining high strength. In this work, mesoscale bend bars (314 × 22 × 18 µm) of 3Y-TZP fabricated using the LM-RIF process were heat treated at 1400 °C for 1 h, 8 h, or 16 h, respectively, to obtain samples with different grain sizes. Strength tests were performed under three-point bending and results were evaluated using Weibull statistics. Fractographic and confocal Raman spectroscopic analyses were carried out to interpret the data.

Experimental findings showed that the characteristic strength decreased with increasing grain size contrary to the damage tolerance hypothesis. An Orowan-Petch model was recalled to correlate the strength with the flaw size to grain size ratio. At fine grain sizes the strength was controlled by the flaws introduced by the LM-RIF process, whereas at large grain sizes the strength become more grain size controlled. Although larger-grained samples did have a higher propensity to transform, and thus increase toughening, exaggerated grain growth in some of the specimens tested caused an additional flaw population which led to an overall lower strength. Finally, based on the experimental observations and fracture mechanics considerations, we believe that an upper bound of ∼2.5 GPa exists for the strength of mesoscale as-fabricated 3Y-TZP ceramic parts.

显微外科手术器械是中型陶瓷的新应用，该中型陶瓷是通过快速脱模成型（LM-RIF）工艺形成的。仪器的强度和可靠性是此敏感应用程序最关注的问题。据推测，增加晶粒尺寸可以改善与3Y-TZP材料中的相变韧化相关的零件的耐损伤性，同时保持较高的强度。在这项工作中，使用LM-RIF工艺制造的3Y-TZP的中尺度弯曲棒（314×22×18 µm）分别在1400°C热处理1 h，8 h或16 h，以获得具有不同的晶粒尺寸。在三点弯曲下进行强度测试，并使用威布尔统计量评估结果。进行了分形和共聚焦拉曼光谱分析以解释数据。

实验结果表明，特征强度随晶粒尺寸的增加而降低，这与损伤耐受性假设相反。召回了Orowan-Petch模型，以将强度与缺陷尺寸与晶粒尺寸的比率相关联。在细晶粒尺寸下，强度由LM-RIF工艺引入的缺陷控制，而在大晶粒尺寸下，强度受到更多晶粒尺寸的控制。尽管大晶粒样品确实具有较高的转变倾向，从而增加了增韧性，但某些测试样品中晶粒的过大生长导致了额外的缺陷，从而导致整体强度降低。最后，基于实验观察和断裂力学考虑，我们认为中尺度的3Y-TZP陶瓷零件的强度上限约为2.5 GPa。