ABSTRACT The need to reduce the energy consumed and the carbon footprint generated by firing ceramics has stimulated research to develop consolidation techniques operating at lower temperatures, ideally not exceeding 300 °C. This has been realised in Ultra Low Energy Sintering (ULES) using high pressure (hundreds of MPa) in the presence of a transient liquid phase, which accelerates plasticity, grain boundary/surface diffusion and mass transport. Several ULES techniques have been developed in the past 50 years, and a common feature of all of them is low temperature consolidation, through mechanisms not yet fully understood, enabling multi-material integration (e.g. organics and inorganics). This research could transform the traditional firing of functional and structural materials. Early stage work on ULES, started in the 1960s, clearly demonstrated cohesion between the compacted particles exceeding what was possible if simply produced by Van der Waals bonding, suggesting the formation of primary inter-particle bonds. Surprisingly, metals Cold Sintered (CS) in dry conditions at room temperature can be even stronger than their counterparts sintered at high temperatures (typically ≈ 2/3 Tm). Hydrothermal Hot Pressing (HHP) was originally conceived in the context of sustainability and environmental preservation, with some examples being the concept of ‘synthetic rock’ for immobilisation of toxic/radioactive waste and the consolidation of high surface area porous ceramics for filtration. Follow up work on HHP considered the possibility of recreating in the lab bio-mineralisation using hydroxyapatite and bioglass (including hybrids) as proof of concept. Recent work on the Cold Sintering Process has demonstrated the potential to bridge the processing gap of multi-material devices (sensors, batteries, 5G antennas, electronic components and biomaterials), enabling integration of polymers, ceramics and metals without degradation of the individual components both at the bulk and interface level. The absence of heating unlocks grain boundary design to an unprecedented level, offering further degrees of freedom in tuning functional properties. This review provides a wide perspective on room temperature consolidation, and covers the related but fragmented work published (≈ 450 papers) during the past 50 years, encompassing the relevant work developed in different disciplines including chemistry, physics, biology and geoscience. Liquid-assisted or liquid-mediated phenomena involving diffusion, plasticity, rheology, and grain growth are still largely unexplored in material science. The purpose of bringing together this literature is to build a general and multidisciplinary knowledge to guide future research directions. Both the reduction of energy consumption and carbon footprint are driving the growing interest in ULES, which could reinvent the concept of sintering, ‘rendering kilns obsolete’. Also, ULES has the potential to produce new classes of materials that cannot be fabricated using conventional routes.

中文翻译：

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冷烧结工艺综述

摘要 减少能源消耗和陶瓷烧制产生的碳足迹的需要刺激了研究开发在较低温度下运行的固结技术，理想情况下不超过 300 °C。这已在瞬态液相存在下使用高压（数百兆帕）的超低能烧结 (ULES) 中实现，从而加速塑性、晶界/表面扩散和传质。在过去的 50 年中，已经开发了几种 ULES 技术，所有这些技术的共同特点是低温固结，通过尚未完全了解的机制实现多材料集成（例如有机物和无机物）。这项研究可以改变功能和结构材料的传统烧制方式。ULES 的早期工作，始于 1960 年代，清楚地证明压实颗粒之间的内聚力超过了简单地通过范德华键产生的可能，这表明形成了初级颗粒间键。令人惊讶的是，在室温干燥条件下冷烧结 (CS) 的金属甚至比在高温下烧结的金属（通常 ≈ 2/3 Tm）更坚固。水热热压 (HHP) 最初是在可持续性和环境保护的背景下构思的，其中一些例子是用于固定有毒/放射性废物的“合成岩石”概念以及用于过滤的高表面积多孔陶瓷的固结。HHP 的后续工作考虑了使用羟基磷灰石和生物玻璃（包括混合体）作为概念证明在实验室中重新创建生物矿化的可能性。最近关于冷烧结工艺的工作已经证明有潜力弥合多材料设备（传感器、电池、5G 天线、电子元件和生物材料）的加工差距，从而实现聚合物、陶瓷和金属的集成，而不会降解单个组件在批量和界面级别。没有加热将晶界设计解锁到前所未有的水平，为调整功能特性提供了更大的自由度。这篇综述为室温固结提供了广阔的视角，涵盖了过去 50 年发表的相关但零散的工作（约 450 篇论文），包括在不同学科（包括化学、物理学、生物学和地球科学）中开展的相关工作。液体辅助或液体介导的现象，包括扩散、可塑性、在材料科学中，流变学和晶粒生长在很大程度上仍未得到探索。汇集这些文献的目的是建立通用的多学科知识，以指导未来的研究方向。能源消耗和碳足迹的减少推动了人们对 ULES 日益增长的兴趣，它可以重塑烧结、“淘汰窑炉”的概念。此外，ULES 有可能生产无法使用传统工艺制造的新型材料。这可以重塑烧结的概念，“淘汰窑炉”。此外，ULES 有可能生产无法使用传统工艺制造的新型材料。这可以重塑烧结的概念，“淘汰窑炉”。此外，ULES 有可能生产无法使用传统工艺制造的新型材料。