METHOD FOR MODIFYING SURFACE OF PISTON FOR INTERNAL COMBUSTION ENGINE, AND PISTON FOR INTERNAL COMBUSTION ENGINE

WIPO Patent Application WO/2014/057935

A1

Provided is a piston for internal combustion engines which suffers no decrease in strength even in high-temperature environments. In a space in which oxygen is present, an aluminum-silicon alloy piston for internal combustion engines is subjected to a first jetting treatment in which iron-based alloy shots having a particle diameter of 20-200 µm, a thermal conductivity at 25°C of 30 W/m·k or less, and a specific gravity of 7.5 g/cm3 or higher are jetted against the surface of the piston under the conditions of an arc height value of 0.07-0.13 mm(N) and successively to a second jetting treatment in which the shots are jetted against the piston surface under the conditions of an arc height value of 0.13-0.22 mm(N). Thereafter, a heat treatment is given to the piston surface at 170-190°C for 1.5 hours or longer in the presence of oxygen to form a surface modification layer in the range from the outermost surface to a depth of about 30 µm, the layer having a structure that includes an intergranular oxide constituted of an oxide of an aluminum-iron alloy at the boundaries of crystal grains of aluminum and/or an aluminum-based alloy.

FUJIWARA NOBUYUKI (JP)
MIYASAKA YOSHIO (JP)

PCT/JP2013/077340

April 17, 2014

October 08, 2013

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ART METAL MFG CO LTD (JP)
FUJI KIHAN CO LTD (JP)

C23C24/04; B24C1/10; B24C11/00; F02F3/00; F16J1/01

JP2008051091A	2008-03-06
JP2011052322A	2011-03-17
JP2002301663A	2002-10-15
JPH0586443A	1993-04-06
JP2008051091A	2008-03-06
US7767033B2	2010-08-03
US8231741B2	2012-07-31

See also references of EP 2907895A4

OGURA, MASAAKI (JP)
Masaaki Ogura (JP)

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