Tubular member for exhaust gas treatment device and exhaust gas treatment device using the tubular member, and method of manufacturing tubular member for exhaust gas treatment device

A method of manufacturing a tubular member for an exhaust gas treatment device including a tubular main body made of a metal and an insulating layer formed at least on an inner peripheral surface of the tubular main body,

• the method comprising:
• preparing a tubular main body;
• and
• forming an insulating layer on an inner peripheral surface of the tubular main body,
• wherein the insulating layer contains glass containing a crystalline substance, and
• wherein the insulating layer has a porosity of from 1% to 12%.

A tubular member for an exhaust gas treatment device, comprising:

• a tubular main body made of a metal;
• and
• an insulating layer formed at least on an inner peripheral surface of the tubular main body,
• wherein the insulating layer contains glass containing a crystalline substance and containing silicon, boron, and magnesium,
• wherein the insulating layer has a porosity of from 1% to 12%, and has a porosity of from 1% to 6% in a range of from the interface between the insulating layer and the tubular main body to 50 μm of the insulating layer,
• wherein the insulating layer contains a pore, which is prevented from being brought into contact with an interface between the insulating layer and the tubular main body, and which has a maximum size of 50 μm or less;
• and a pore, which is brought into contact with an interface between the insulating layer and the tubular main body, and which has a maximum size of 30 μm or less, and
• wherein the insulating layer has a softening temperature of 850° C. or more.