Metals surfaces coated with ceramics are part of the field of metal-ceramic composite with special applications. In these applications, devices, metal parts are coated with a ceramic coating that improves the properties of the metal as: corrosion resistance, wear resistance or provide special biological properties such as development and anchoring of living cells on ceramic layer (consisting for example of hydroxyapatite). Coatings for metal prosthetic components can be made by various techniques and methods. Coating process of metallic implants with hydroxyapatite layers (and others) must be a series of steps and requirements that lead to a strong binding ceramic layer of metal support, and in some cases, to achieve the maximum density of the coating that protects the
metal support of corrosion phenomena.
So, which is the best method for obtaining controlled surface properties (chemical composition, roughness, porosity) needed in the field of biomaterials used in implantology?
May have to consider texture of materials as well. These can play a major role in how coatings will deposit on materials
The best way to prepare the surface by thermal spraying - it's sand blasting with corundum powder. Depending on the method of spraying and spraying material used corundum powders with different grain size: coarser than the grains, the more roughened surface.
For spraying ceramic materials normally used corundum powders having a particle size of 1-2 mm (F008 - F022, http://www.kuhmichel.com/index.php?article_id=44&clang=0). When more fine powders, the surface roughness may become insufficient for engaging with the ceramic layer.
For the spraying of metal or metall-ceramic coatings by HVOF or HVAF using surface preparation with finer corundum: F040-F090.
The larger grains of corundum, the faster they are destroyed during sandblasting. Therefore, coarse powders have to be changed frequently.
Does your question relate to the surface quality of the metallic surface before coating or to the surface quality of the coating material?
Sorry, to 'answer' you with another question, but your question is unclear to me
Selecting the best coating process for biomedical devices is, indeed, dependent on many criteria. There are controversial findings, each stating that one of the methods is the most effective in improving biomedical devices’ surface properties.
I suggest you to read some review papers that have tried to critically investigate the advantages and disadvantages of each method. I, personally, believe that a research group should consider various criteria, beside the performance of the coating, to select the coating process. One of the most important factors is financial aspects of coating method. For instance, plasma sputtering is a high-tech method which does not seem to be the right choice for low budget research groups. Conversely, dip-coating method could be easily set up and there are many researches that are not conducted yet. In some cases, the coating process requires much of maintaining expenditures. For instance, PVD coating equipment could require a lot of maintaining expenditure in addition to the initial investment while the coatings are proven to be unstable.
To be brief, one should consider a wide range factors to be able to decide about founding the right research methodology. Nonetheless, I have found the attached research papers scientifically accurate in evaluating the coating methods used for biomedical metallic devices.
I think that chemical properties (chemical composition) are more relevant than texture (roughness or porosity) to implatology.
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