Abstract

Metal objects are treated by anodising the metal object in contact with an aqueous electrolyte, and then subjecting the anodised metal object to a reversed voltage. The anodising is performed in two stages, firstly to passivate with the formation of an oxide layer, and secondly to form regions in the oxide layer having a higher oxygen to metal atom ratio, for example pits or caps, in this oxide layer. The second stage of anodising is performed by applying a multiplicity of voltage cycles, each voltage cycle involving ramping the voltage between a lower threshold voltage and an upper threshold voltage, and then returning to the lower threshold voltage. The reversed voltage step forms a hydrous metal oxide in the regions of higher oxygen to metal atom ratio, and the oxide layer and hydrous metal oxide together constitute a surface layer which is integral with the metal object, and has ion exchange capacity. After the reversed voltage step the metal object is then contacted with a bio-effective material such as a biocidal metal, which is absorbed into the surface of the metal object. The processing time may be reduced by applying the multiple voltage cycles. The invention also provides a treated metal object which can be prepared by treating a metal object having a micro-rough surface according to the method described above.

IPC Classes  ?

• A61L 27/04 - Metals or alloys
• A61L 27/06 - Titanium or titanium alloys
• A61L 27/50 - Materials characterised by their function or physical properties
• A61L 27/54 - Biologically active materials, e.g. therapeutic substances

Abstract

A method of applying a coating to a substrate material (30) for use as a composite body wherein the material is a polymer or a ceramic, which method comprises plasma spraying a powder such as zirconia or titania onto the substrate material to form an initial layer (32). Coatings of other materials such as titanium metal (34) or hydroxyapatite (36) can subsequently be deposited directly or indirectly onto the initial layer (32). The initial layer (32) avoids problems of poor adhesion.

IPC Classes  ?

• C04B 41/89 - Coating or impregnating for obtaining at least two superposed coatings having different compositions
• A61L 27/30 - Inorganic materials

Abstract

In a process for anodising a metal object (12), the metal object (12) is contacted with an anodising electrolyte (32), and is first pre-anodised so as to grow a thin oxide film on the surface. The microscopic surface area is then deduced from electrical measurements either during pre-anodising or on the pre-anodised surface. The metal object (12) can then be anodised. This is applicable when treating an implant to provide a surface that has the ability to incorporate biocidal material such as silver ions. The pre-anodising uses a low voltage, for example no more than 2. V, and may take less than 120 seconds.

IPC Classes  ?

• C25D 11/16 - Pretreatment
• C25D 21/12 - Process control or regulation
• C25D 11/02 - Anodisation

Abstract

Metal implants (10) are treated by anodising the surface (11, 12) in contact with an electrolyte, and then briefly subjecting the anodised surface to a reversed voltage. During a first anodising stage the surfaces are passivated, while during a subsequent anodising stage pits are formed in the passivating surface layer. Rough portions (15) of the surface, in particular portions produced by plasma spraying of metal powder, are sealed with a watertight cover (20) during at least part of the anodising process. After rinsing, biocidal metal ions are subsequently absorbed into the surface of the implant. This provides the implant with biocidal properties. The use of the cover (20) enables a more uniform geometric distribution of biocidal metal ions to be achieved.

IPC Classes  ?

• C25D 5/02 - Electroplating of selected surface areas
• C25D 11/02 - Anodisation
• C25D 11/26 - Anodisation of refractory metals or alloys based thereon
• A61L 27/00 - Materials for prostheses or for coating prostheses