CHAPTER 4
INTRODUCTION TO
WEAR & WEAR MECHANISMS
1
4.1 Introduction
•
Wear
is
the surface damage
or
the removal of the
material
from the surface of a solid body as a result of
mechanical action of the counter body. /sliding, rolling
or impact motion/.
•
Wear may combine effects of various
physical and
chemical processes
proceeding during the friction
between two counteracting materials:
micro-cutting
micro-ploughing
plastic deformation
cracking
fracture
welding and melting
3
.
4
•
There are five different types of wear (wear
mechanisms):
adhesive, abrasive, fatigue, corrosive
and erosive wear
.
•
In many cases, the combinations
of the
adhesive,
corrosive and abrasive forms of wear occur
:
two-thirds of all wear encountered in industrial
situations occurs because of adhesive-and
abrasive wear mechanisms.
•
Wear
by
all
mechanisms
except
by
fatigue
mechanism
, occurs by gradual removal of material.
Objective
:
to understand the
wear mechanisms
and
control methods
.
5
4.2 Wear mechanisms
•
Wear occurs by
mechanical action
and is generally
accelerated by
frictional heating
(or thermal means).
•
Wear
includes
five
principal
,
quite
distinct
phenomena
that have only one thing in common: the
removal of solid material from rubbing surfaces.
•
Types of wear are:
1.
Adhesive wear
2.
Abrasive wear
3.
Fatigue wear
4.
Corrosive wear
5.
Erosive wear
6
4.2.1
Adhesive wear
•
Adhesive wear occurs
when two normally flat
bodies are in sliding contact .
•
The load applied is so high that adhesion (or
bonding) and deformation occurs at the asperity
contacts at the interface, and these contacts are
sheared by sliding.
•
The motion of the rubbing counter bodies result in
rupture of the micro-joints. Thus some of the material
is transferred by its counter body.
7
.
metal
8
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- Fall '19
- Msc. Amar Yemim
