However, if new materials are used to form a composite layer structure, such as carburized layer and oxide layer, you can apply for a utility model patent.
For example, the technical scheme of "plating a new layer of material on the film composite layer on the surface of the product to solve specific technical problems" can be considered to apply for a utility model patent.
However, at this time, we must pay attention to the writing of the claim. What is required to be protected is neither the material features themselves nor the products made of new materials. Such writing cannot be authorized. Instead, it should be written as a structural feature of a thin film composite layer or a product with the characteristics of a thin film composite layer. In addition, it is best not to write new material features into the claims.
For the relevant basis, please refer to the relevant chapter on utility model examination in the Examination Guide (I can't remember the specific content, but you can search for keywords such as composite layer structure, new material/known material characteristics).