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Ali Alirezaie

Grade:  Master

 

Thesis Title:

Experimental Analysis of Composite Materials using Laser Cladding Procces and Calculation of Stress and Temperature Fields by Finite Element Method

Year: Sept. 2012- Jan. 2015.

Abstract:

Since cladding operation improves the function of the part’s surface in addition to its useful life enhancement, it increases the parts’ value. Nowadays, utilizing the metalceramic composite coatings is highly noticed by a lot of industries and it’s because of the high thermal resistance, high wearing resistance, high strength of the ceramics and also ductility and toughness of the metals. By combination of these properties, some unique features can be developed. The composite coatings are often used in order to wearing and corrosion resistance enhancement. Laser cladding process is one of the surface cladding methods which is applied by many industries. In this process part of the laser beam’s energy is absorbed by the cladding powder and results the powder’s melting before reaching the substrate, another part of the energy melts a thin layer of the substrate and therefore a powerful bond is developed between the coating and the substrate in addition to the least dilution. In this investigation, with the aid of laser the cladding process is analyzed in order to develop the Nickel-Titanium Carbide cladding composite in the views of experimental and finite element. In the experimental, by providing and featuring theessential equipment of this process such as designing and making the dual power feeder and featuring the cladding head, this process is analyzed by the Nd:YAG laser and CO2 laser .Because of the low power In utilizing the CO2 laser, it’s not possible to develop the coatings with suitable width. By applying the Nd:YAG laser the appropriate parameters are determined with proper width and thickness. Titanium Carbide cladding composite is developed under metallography and mechanical tests with different percentages of hard phases. The results show that the Titanium Carbide particles are spread out through the nickel matrix, Because of the particles’ lightness the spread of these particles is also more on the surface. Wear test results show that the coating’s wear resistance and its friction is reduced by increasing the amount of Titanium Carbide. The coating’s hardness is increased by increasing the hard phase percentage. In the finite element investigation, the cladding process is modeled with the help of laser in order to determining the thermal and stress distribution. The finite element software Abaqus is used for modeling. The element birth and death technique is used for simulating. By moving the laser beam on the substrate surface, first the free end bends towards down, after reaching the model’s temperature to the environment’s temperature, the thermal stresses change and the model curvature bends towards above. By increasing the coating’s Titanium Carbide percentage
the amount of curvature is decreased. The residual stress in the coating is a pressure type and by increasing the amount of Titanium Carbide this stress increases. The residual stress is constant along the cladding.

Keywords: Laser cladding, Powder feeder, Metal-ceramic composite, Nickel-Titanium
Carbide, Wear test, Finite element, Element birth and death

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