Control of the localized electrochemical dissolution of solid-state sintered silicon carbide – SiCECM

固态烧结碳化硅局部电化学溶解的控制 – SiCECM

• 批准号: 527413836
• 负责人: Professor Dr. Alexander Michaelis
• 金额: --
• 依托单位: Professur für Anorganisch-Nichtmetallische Werkstoffe
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/527413836?language=en
• 关键词: Control; localized; electrochemical; dissolution; solid

Due to their very good mechanical, tribological and corrosion-resistant properties, solid-state sintered SiC ceramics (SSiC) are used, for example, as mechanical seals or valves in power plant construction and chemical industry. However, their high hardness and compressive strength make mechanical shaping and surface treatment difficult. The high melting point impairs thermal machining by spark erosion or laser ablation. Electrochemical machining (ECM) represents a promising alternative due to the subordinated influence of mechanical and thermal workpiece properties. But there are currently severe limitations with regard to applicable machining parameters for targeted shaping and surface structuring. Own preliminary studies of both applicants prove basic solutions for anodic dissolution of SSiC with sufficiently high electrical conductivity for the required charge exchange. Passivating layers are formed, and dielectric breakthrough occurs with considerable formation of oxygen through electrolysis at sufficiently high electric potential. More detailed investigations into oxide layer formation and dissolution, possible side reactions and pH value changes as well as effects on the instability of the passive layer are not yet known, and there is no uniform description of the ECM in thermodynamic imbalance. In addition, the observed influence of Joule heating on the removal rate due to the semiconductor properties of SSiC has not yet been investigated. Jet-ECM enables the application of sufficiently high voltages and individual electrolyte composition for the dissolution of SSiC with high localization through strongly focusing the current flow and thus represents a promising method for researches on surface structuring. However, predictable ablation geometries and the impact of local Joule heating on the current efficiency are not known. In order to analyze relevant, interacting field quantities and field quantity distributions in sufficiently small time scales and geometry dimensions and to understand their relationships, numerical simulation models appear useful and necessary. The main goal is the fundamental research of the influences of process input parameters on the anodic dissolution of SSiC for simulation-assisted design of micro-structuring by Jet-ECM. For this purpose, the trans-passive breakthrough and removal continuity at lower electric potential will be investigated. Basic knowledge gained in a micro-capillary cell shall provide the necessary input parameters for the development of a simulation model for the scaling of Jet-ECM processing parameters. The oxygen evolution and carbon reaction shall be quantified in order to derive the oxidation states of Si and C and their stoichiometry and to control the removal geometry.

由于其非常好的机械、摩擦学和耐腐蚀性能，固态烧结SiC陶瓷（SSiC）被用作例如发电厂建设和化学工业中的机械密封或阀门。然而，它们的高硬度和抗压强度使得机械成型和表面处理变得困难。高熔点损害了通过电火花腐蚀或激光烧蚀的热加工。电解加工（ECM）是一种很有前途的替代方案，由于机械和热工件性能的从属影响。但是，目前对于用于目标成形和表面结构化的适用加工参数存在严重的限制。两个申请人自己的初步研究证明了用于SSiC的阳极溶解的基本解决方案，其具有足够高的电导率以用于所需的电荷交换。形成钝化层，并且通过在足够高的电势下电解而大量形成氧而发生电介质击穿。对氧化层形成和溶解、可能的副反应和pH值变化以及对钝化层的不稳定性的影响的更详细的调查尚不清楚，并且在热力学不平衡中没有对ECM的统一描述。此外，由于SSiC的半导体性质，焦耳加热对去除率的影响尚未被研究。喷射电解加工能够通过强烈聚焦电流流动来施加足够高的电压和单独的电解质组合物以溶解具有高局部化的SSiC，因此代表了用于表面结构化研究的有前途的方法。然而，可预测的烧蚀几何形状和局部焦耳加热对电流效率的影响是未知的。为了分析相关的，相互作用的场量和场量分布在足够小的时间尺度和几何尺寸，并了解它们之间的关系，数值模拟模型显得有用和必要。本文的主要目的是研究工艺参数对SSiC阳极溶解的影响，为射流电解加工微结构的仿真辅助设计提供基础。为此，将研究在较低电势下的跨式被动穿透和去除连续性。在微毛细管池中获得的基本知识应提供必要的输入参数，用于开发射流ECM处理参数缩放的模拟模型。应量化析氧和碳反应，以得出Si和C的氧化态及其化学计量，并控制去除几何形状。