.


:




:

































 

 

 

 





. 50- .

. , , , . . .

. , . , .

, . , . , .

. , , , .

. , "". . , , , , , , . 3-4 , 4,5 . .

. , , . , .

HARDFACING

Hardfacing is the process of applying by welding, plasma spraying or plating a layer, edge or point of a wear-resistant metal on a metal part to increase its resistance to abrasion, erosion, hammering or other forms of wear. Hardfacing may be applied to new parts to improve their resistance to wear during the service or to worn parts for the purpose of restoring them to the serviceable condition. In general the wear-resistant coating is applied only to those critical surfaces of components where wear is maximum. Worn parts can be satisfactorily re faced or rebuilt many times before the replacement becomes obligatory.

Alloys, which are used for hardfacing should possess the following properties:

1) good resistance to heat and oxidation;

2) good resistance to impact and thermal loads;

3) good corrosion resistance;

4) high hot-hardness;

Both ferrous and non-ferrous alloys are used for hardfacing. They are: austenitic manganese steel, cobalt-base alloys, aluminium bronzes, beryllium copper alloys. Of the latest use titanium carbides should be mentioned specially because of their high properties.

Powder Alloys. Many of the alloys available for hardfacing are produced as powders. Some of the powders are used for spray-coating processes for protecting metal surfaces but high percentage of powders are pressed and sintered approximately to the final shape that then can be machined to a desired shape.

, , , , . . , . .

, :

1) ;

2) ;

3) ;

4) ;

, . : , , , . , - .

. . , , .





:


: 2016-11-18; !; : 525 |


:

:

.
==> ...

1716 - | 1500 -


© 2015-2024 lektsii.org - -

: 0.008 .