Composite member

A composite member made of a composite of magnesium or a magnesium alloy and SiC, characterized by

• containing 50 volume % or more said SiC,
• having a network portion bonding said SiC to each other, and
• having a coefficient of thermal expansion not lower than 4 ppm/K and not higher than 8 ppm/K.

A composite member, characterized by comprising:

• a substrate composed of a composite material made of a composite of magnesium or a magnesium alloy and SiC and containing 50 volume % or more SiC;
• and
• a metal coating layer covering at least one surface of said substrate.

A composite member manufacturing method of manufacturing a composite member including a substrate composed of a composite material made of a composite of magnesium or a magnesium alloy and SiC, by infiltrating an SiC aggregate accommodated in a cast with molten magnesium or magnesium alloy, characterized in that

• SiC powders are used to form a molded body smaller in volume than said cast and this molded body is used as said SiC aggregate, and
• said molded body is arranged in said cast and a metal coating layer covering at least one surface of said substrate is formed with said molten magnesium or magnesium alloy that flows into a gap produced between said cast and said molded body.

A composite member manufacturing method of manufacturing a composite member including a substrate composed of a composite material made of a composite of magnesium or a magnesium alloy and SiC, by infiltrating an SiC aggregate accommodated in a cast with molten magnesium or magnesium alloy, characterized in that

• SiC powders are used to form a molded body smaller in volume than said cast and this molded body is used as said SiC aggregate, and
• said molded body is arranged in said cast and a spacer is arranged to maintain a gap between said molded body and said cast, so that a metal coating layer covering at least one surface of said substrate is formed with said molten magnesium or magnesium alloy that flows into said gap.

A composite member manufacturing method of manufacturing a composite member including a substrate composed of a composite material made of a composite of magnesium or a magnesium alloy and SiC, by infiltrating an SiC aggregate accommodated in a cast with molten magnesium or magnesium alloy, characterized in that

• said cast has a surface of contact with said SiC aggregate and a thermal expansion portion made of a material higher in coefficient of thermal expansion than SiC, and
• said SiC aggregate is arranged in said cast, said thermal expansion portion expands by heat generated in infiltrating the SiC aggregate with said molten magnesium or magnesium alloy to thereby produce a gap between said surface of contact and said SiC aggregate, and thus a metal coating layer covering at least one surface of said substrate is formed with said molten magnesium or magnesium alloy that flows into said gap.

A method of manufacturing a composite member made of a composite of magnesium or a magnesium alloy and SiC, characterized by comprising:

• an infiltration step of forming an infiltrated plate by infiltrating an SiC aggregate accommodated in a cast with molten magnesium or magnesium alloy;
• and
• a cooling step of cooling said infiltrated plate in one direction from a side of said infiltrated plate opposite to a side of supply of said molten magnesium or magnesium alloy so as to solidify said molten magnesium or magnesium alloy.

A composite member made of a composite of magnesium or a magnesium alloy and SiC, characterized in that

• said composite member is a plate member having a sufficient size from which a circular region having a diameter exceeding 50 mm can be taken, and
• with a straight line passing through center of gravity when the composite member is two-dimensionally viewed being defined as a section line, a cross-section in a direction of thickness of said composite member is taken, a range in this cross-section extending over up to 10% of a length of said section line is defined as a central region with said center of gravity serving as a center, any small region of 1 mm×1 mm is taken from this central region, and when a ratio of an area of a defect portion with respect to an area of the small region is defined as an area ratio, said area ratio is not higher than 10%.

A composite member manufacturing method of manufacturing a composite member including a substrate composed of a composite material made of a composite of magnesium or a magnesium alloy and SiC, by infiltrating an SiC aggregate accommodated in a cast with molten magnesium or magnesium alloy, characterized by comprising a metal coating layer formation step of stacking a metal plate on said substrate and pressurizing this stack with a pressure not lower than 0.5 ton/cm2 while the stack is heated to a temperature not lower than 300° C.