DigiChrom: A Domain Ontology for Semantic Representation of Trivalent Chromium Platings and Its Large Language Model‐Based Alignment With Multiple Mid‐Level Ontologies

Electrodeposition is a key surface engineering technology, with chromium coatings widely used to improve tribological, corrosion‐resistant, and aesthetic properties. Due to environmental regulations such as REACH, industry is transitioning from hexavalent to trivalent chromium (Cr(III)) electrolytes. These systems exhibit high physicochemical complexity and strong sensitivity to process fluctuations and contaminants, making conventional trial‐and‐error optimization inefficient. As a result, data‐driven approaches combining experimental and simulation data with machine learning are increasingly used to investigate complex process–structure–property relationships. The effectiveness of these approaches depends on FAIR‐compliant, well‐structured datasets. Semantic web technologies, particularly ontologies, enable the formal representation of domain knowledge and the integration of heterogeneous data into machine‐actionable information. Within the German Platform MaterialDigital (PMD) initiative, domain‐specific ontologies support a federated materials data infrastructure. This work presents two main contributions, namely, the PlatOn ontology, developed in the DigiChrom project to semantically represent galvanic chromium plating and material characterization, and a hybrid Large Language Model (LLM)‐assisted alignment pipeline that maps PlatOn to the PMD Core Ontology (PMDco 3.0) and the Basic Formal Ontology (BFO). This ensures interoperability and enables cross‐ontology querying of electroplating data. Ontology development is supported by a graph‐based engineering workflow using the BWMD mid‐level ontology and the Graph Designer App.