Roman metalworking crucibles are frequently characterized by an extra outer layer of clay, applied to a pre‐formed vessel. Three‐point bending and standardized dead‐weight loading tests were conducted to determine the advantages offered by the extra outer layer. Deformation and fracture behaviour, at temperatures up to 1100°C, of two‐layer, monolithic and tempered‐monolithic briquettes were compared. Measurements indicated that the two‐layer briquettes were more resistant to fracture at high temperatures: > 850°C they showed more extensive plastically deformed regions than monolithic briquettes. The influence of temper was consistent with previous results: tempering caused quasi‐stable fracture and reduced fracture strength. The results suggest extra outer layers assisted in preventing catastrophic failure.

中文翻译：

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两层陶瓷的高温性能及其对罗马坩埚的影响

罗马金属加工坩埚通常以涂在预制容器上的额外外层粘土为特征。进行了三点弯曲和标准化的自重载荷测试，以确定额外的外层提供的优势。比较了两层整体和回火整体煤球在最高1100°C的变形和断裂行为。测量表明，两层煤球在高温下更耐断裂：> 850°C，它们显示出比整体煤球更大的塑性变形区域。回火的影响与以前的结果一致：回火导致准稳定的断裂，断裂强度降低。结果表明，额外的外层有助于防止灾难性故障。