Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, 2003 / Systematic laser cladding experiments were performed using a mixture of a Nickel
base alloy powder mixed with tungsten carbide powder (percentage contents of
tungsten carbide from 10% to 40%) on EN8 steel substrate with pre-placed powder
method. Laser cladding of the Nickel base alloy powder + 50% tungsten carbide
powder on EN9 steel substrate was performed with powder injection method as well.
A Finite Element Method for calculating the surface temperature distribution was
used to help prediction of temperature distribution laser cladding results. Composition
of cladding materials was designed; a sticking agent was chosen for the pre-placed
powder method. Clad coatings were obtained for different process parameters for
laser cladding, and a detailed study of the affects of these parameters has been carried
out.
The characteristic microstructure and properties of the clad layers and interface were
investigated by using an optical microscope, a micro hardness tester and a makeshift
wear test. A comprehensive review is presented on the dilution of the coating and the
typical problems experienced with the coating substrate interface.
The results show that microstructure of clad layers comprise three zones: the cladding
layer, bonding zone and heat-affected zone. The results showed that tungsten carbide
particles increased the hardness and wear resistance as expected. Wear resistance of
laser cladding coating is 3.5 times than that of substrate. The micro hardness range of
the cladding layer is from RV 981.5 to RV 1187, which is 2-3 times than that of
substrate. The micro hardness varies from cladding coating to transition layer then to
heat affected zone and substrate along a gradient.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:cput/oai:localhost:20.500.11838/1267 |
| Date | January 2003 |
| Creators | Yang, Wen Fu |
| Publisher | Peninsula Technikon |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | http://creativecommons.org/licenses/by-nc-sa/3.0/za/ |
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