Magnesium Elektron, Inc.

Timothy E Wilks

Paul Lyon

Mark Turski

Matthew Murphy

Hossein Karimzadeh

Phillip David Rogers

Sarka Jeremic

A magnesium alloy suitable for use as a corrodible downhole article. The alloy has a corrosion rate of at least 50 mg/cm/day in 15% KCl at 93&#xb0; C. and a 0.2% proof strength of at least 50 MPa when tested using standard tensile test method ASTM B557-10.

Corrodible downhole article

A corrodible downhole article includes a magnesium alloy. The magnesium alloy includes: 1-9 wt % Zn; 1-2 wt % Cu; 0.5-1.0 wt % Mn; and 0.1-5 wt % of a corrosion promoting element (e.g., Ni). The alloy can have a 0.2% proof strength of at least 150 MPa when tested using standard tensile test method ASTM B557-10.

A magnesium alloy is suitable for use as a corrodible downhole article, wherein the alloy includes:

A magnesium alloy is suitable for use as a corrodible downhole article, wherein the alloy includes: (a) 11-15 wt % Y, (b) 0.5-5 wt % in total of rare earth metals other than Y, (c) 0-1 wt % Zr, (d) 0.1-5 wt % Ni, and (e) at least 70 wt % Mg. It has been surprisingly found by the inventors that by increasing the Y content of the alloy to the range specified above, increased age hardening response and hence increased 0.2% proof stress can be achieved.

The invention relates to composite sacrificial anodes, particularly but not exclusively, based on magnesium, and to methods for their production. The composite sacrificial anode () for immersion in a corrosive environment comprises a plurality of castings () of a sacrificial material each disposed around a corresponding electrical connector for attachment to a structure to be protected, at least a part of the surface of each segment () being protected from corrosion by the environment by being adjacent at least one other segment (), wherein the castings are connected together electrically only via their electrical connectors. A method of producing a composite sacrificial anode for immersion in a corrosive environment is also described, the anode () having an electrical connection for attachment to the structure to be protected, which method comprises casting a plurality of segments () of a sacrificial material each in contact with a corresponding electrical connector, each connector being at least partly within its corresponding individual segment (), and electrically connecting the segments together only via their electrical connectors.

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Manchester, United Kingdom

Timothy E Wilks