Vehicular disc brake rotor and manufacturing method of vehicular disc brake rotor

Patent metadata

Field	Value
Publication number	US-9541144-B2
Application number	US-201314013468-A
Country	US
Kind code	B2
Filing date	Aug 29, 2013
Priority date	Aug 31, 2012
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

Abstract

A vehicular disc brake rotor is provided with a cast-iron base, a nitrogen diffusion layer formed on the cast-iron base, a nitrogen compound layer formed on the nitrogen diffusion layer, and an iron oxide layer including Fe 3 O 4 and formed on the nitrogen compound layer. In a burnish and a first re-burnish of a “Passenger car-Braking device-Dynamometer test procedures” (which is based on JASO C 406:2000), a change ratio of a frictional coefficient between the burnish and the first re-burnish is 10% or less.

First claim

What is claimed is:

1. A vehicular disc brake rotor comprising:
a cast-iron base;
a nitrogen diffusion layer formed on the cast-iron base;
a nitrogen compound layer formed on the nitrogen diffusion layer; and
an iron oxide layer including Fe 3 O 4 and formed on the nitrogen compound layer,
wherein the iron oxide layer configures a frictional surface, the frictional surface having a pore area ratio of an area with pores to an entire area of the frictional surface being 15% or less, and
wherein, in a burnish and a first re-burnish, a change ratio of a frictional coefficient between the burnish and the first re-burnish is 10% or less.

2. The vehicular disc brake rotor according to claim 1 , wherein a standard deviation of a frictional coefficient is 0.011 or less in a plurality of environment conditions where an absolute humidity is changed within a range of 3 g/m 3 to 35 g/m 3 and a temperature is changed within a range of 10° C. to 40° C., in any of the burnish and the first reburnish.

3. The vehicular disc brake rotor according to claim 1 , wherein a thickness of the nitrogen diffusion layer is 25 μm to 450 μm, a thickness of the nitrogen compound layer is 5 μm to 25 μm and a thickness of the iron oxide layer is 2 μm to 7 μm.

4. The vehicular disc brake rotor according to claim 3 , wherein a mode of statistics of hole diameters of the pore parts is 2 μm or less.

5. The vehicular disc brake rotor according to claim 1 , wherein there is no crack in any of the nitrogen compound layer and the iron oxide layer.

6. The vehicular disc brake rotor according to claim 1 , wherein a standard deviation of a frictional coefficient is 0.011 or less in a plurality of environment conditions where an absolute humidity is changed within a range of 3 g/m 3 to 35 g/m 3 and a temperature is changed within a range of 10° C. to 40° C., in any of the burnish and the first re-burnish,
wherein a thickness of the nitrogen diffusion layer is 25 μm to 450 μm, a thickness of the nitrogen compound layer is 5 μm to 25 μm and a thickness of the iron oxide layer is 2 μm to 7 μm,
wherein a mode of statistics of hole diameters of the pore parts is 2 μm or less, and
wherein there is no crack in any of the nitrogen compound layer and the iron oxide layer.

7. The vehicular disc brake rotor according to claim 1 , wherein the pore area ratio is 15% or less and greater than zero.

8. A manufacturing method of manufacturing the vehicular disc brake rotor according to claim 1 , the manufacturing method comprising:
performing a gas nitrocarburizing treatment for a surface of the cast-iron base, at a treatment temperature of 500° C. to 590° C. to thus form the nitrogen diffusion layer and a nitrogen compound layer, and
when a temperature becomes 400° C. to 480° C. after performing the gas nitrocarburizing treatment, exposing the workpiece to an atmosphere and cooling the workpiece to a room temperature to thus form the iron oxide layer including Fe 3 O 4 on a surface of the nitrogen compound layer.

Assignees

• Akebono Brake Ind

Inventors

• Sugai Yoshiyuki
• Seki Katsuji
• Takada Takuya

Classifications

• F16D65/125

  characterised by the material used for the disc body · CPC title

• C23C8/80

  After-treatment · CPC title

• C23C8/32

  of ferrous surfaces · CPC title

• C23C8/30 Primary

  Carbo-nitriding · CPC title

• F16D65/127 Primary

  characterised by properties of the disc surface; Discs lined with friction material · CPC title