In order to be suitable for tribological applications, polymeric materials, which can usually
exhibit mechanical strength, lightness, ease of processing, versatility and low cost, together
with acceptable thermal and environmental resistances, have to show good abrasion and
wear resistance. This target is not easy to achieve, since the viscoelasticity of polymeric
materials makes the analysis of the tribological features and the processes involved in such
phenomena quite complicated.
Metal cutting puts extreme demands on the tool and tool material through conditions of high forces, high contact pressures, high temperatures, and intense chemical attack by difficult to cut work materials. In addition, the tool geometry and cutting conditions in terms of sharp edges, cyclic engagement and presence of cutting fluid will add to the severity. Most often cutting tools are used close to their ultimate resistance against these loads, especially to the limiting thermal and mechanical stresses. ...
Since the dawn of history, human activities have always been closely related to friction,
the resistance to sliding. It is thanks to friction that one can stand and walk on
the ground, one can wear clothes, one can make fire by rubbing two sticks together,
or one can even start and stop a car. In these cases friction is very useful for human
beings. In many other cases, however, human activities have been very much hampered
by friction since ancient times. How to diminish friction is one of the most
basic technological problems.
For example, when a heavy...
One of the most promising, generally applicable and well-adopted methods to enhance
the surface performance of materials is the use of coatings. The reason is
that it is extremely difficult and expensive to meet homogeneous materials having
on their surface the ensemble of desired properties, such as high hardness, wear
resistance, adequate stiffness, increased ductility, chemical inertness, stainlessness,
controllable electrical and thermal conductivity behavior, etc.
There is no shorthand method of designing machinery for a specified wear life. Thus a step-by-step method is given for designers to follow. The method begins with an examination of worn parts of the type to be improved. The next step is an estimate of stresses, temperatures, and likely conditions of operation of the redesigned machinery. Material testing for wear resistance is discussed, and finally, a procedure is given for selecting materials for wear resistance.
Several developments made high-speed cutting (HSC) possible. HSC became an important trend in machining (Figure 5.2-1). The development of tool materials was a prerequisite to higher wear resistance under high temperatures. Up to the 1960s, the dualism of hardness and wear resistance on the one hand and toughness on the other were dominant limiting factors in tool materials. The functional separation of the ability to carry static and dynamic loads and of tribological functions was established by introducing coatings....
Kenneth C. Ludema Professor of Mechanical Engineering Department of Mechanical Engineering and Applied Mechanics The University of Michigan Ann Arbor, Michigan
6.1 GENERAL PRINCIPLES IN DESIGN FOR WEAR RESISTANCE / 6.1 6.2 STEPS IN DESIGN FOR WEAR LIFE WITHOUT SELECTING MATERIALS / 6.4 6.3 WEAR EQUATIONS / 6.6 6.4 STEPS IN SELECTING MATERIALS FOR WEAR RESISTANCE / 6.7 6.5 MATERIAL-SELECTION PROCEDURE / 6.14 REFERENCES / 6.18 BIBLIOGRAPHY / 6.18
There is no shorthand method of designing machinery for a specified wear life.
I have been familiar with plasma spraying in one of the leading thermal spray research
laboratories in North America; Centre for Advanced Coating Technologies at the
University of Toronto since I started my PhD thesis under supervision of Professors
Javad Mostaghimi and Thomas W. Coyle in 2001. Having access to various methods of
thermal spraying, diagnostic tools, and processes simulation, I gained experiences in
process, deposition, characterization, and simulation of various types of thermal spray
Tungsten Carbide - Processing and Applications, provides fundamental and practical information of tungsten carbide from powder processing to machining technologies for industry to explore more potential applications. Tungsten carbide has attracted great interest to both engineers and academics for the sake of its excellent properties such as hard and wear-resistance, high melting point and chemically inert. It has been applied in numerous important industries including aerospace, oil and gas, automotive, semiconductor and marine as mining and cutting tools, mould and die, wear parts, etc.
The seat or seal rings provide the seating surface for the disk. In some designs, the body
is machined to serve as the seating surface and seal rings are not used. In other designs,
forged seal rings are threaded or welded to the body to provide the seating surface. To
improve the wear-resistance of the seal rings, the surface is often hard-faced by welding
and then machining the contact surface of the seal ring. A fine surface finish of the
seating area is necessary for good sealing when the valve is closed.
Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Patients presenting with miliaria while wearing flame resistant clothing in high ambient temperatures: a case series
Fluid clutches and brakes may be divided into two groups: those containing a ﬂuid only and those containing a mixture of ﬂuids and solids. Those containing only a ﬂuid rely primarily upon the mass of the ﬂuid and secondarily upon its viscosity to transmit torque. Units containing both a ﬂuid and a solid in a particulate form rely upon the suspended solids to provide the major bond between the components that either transmit or resist torque when under the inﬂuence of an external electromagnetic ﬁeld.