Characterising laser metal deposited titanium and molybdenum on titanium alloy for surface engineering applications
- Authors: Ntumba, Eric Muipatay
- Date: 2016
- Subjects: Laser-induced breakdown spectroscopy , Pulsed laser deposition , Lasers - Industrial applications , Titanium powder , Metal coating , Molybdenum
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/212802 , uj:21029
- Description: Abstract: In this work, sample study was done on the characterisation of Ti-10%Mo powder metal produced via LMD. Different process parameters were employed for the LMD process. The laser power was varied between 1kW and 2.2kW while keeping all other parameters constant. The scanning speed of 0.5m/sec, powder flow rate of pure titanium 1.8g/min and the powder flow rate of molybdenum 2g/min. were used for the coatings. The process parameters were carefully selected to represent low, medium and high settings. The characterisations carried out include optical microscopy and Scanning Electron Microscopy combined with Energy Dispersive Spectroscopy (SEM/EDS) techniques to investigate the particle distribution, microstructural evolution and chemical analysis of the welded samples. Vickers microhardness was used to determine the hardness distribution of the coating Ti6Al4V/Ti-Mo, the dry sliding wear tests were carried out on the deposited Ti6Al4V/Ti-Mo samples to determine the sliding wear of samples and corrosion tests was used to obtain information on the corrosion behavior of Ti6Al4V/Ti-Mo in 3.5% NaCl solution. The characterised laser metal deposited Ti6Al4V and Ti-Mo, revealed that the varied laser power played a main part in the microstructural evolution. It was found that the formation of the Widmanstӓtten structures improved the hardness of Ti6Al4V/Ti-Mo. The highest hardness value was found at the top zone of the clad owing to the presence of the reinforcement particles of Ti-Mo, the highest hardness value for all the samples was found at an average of 496HV. The sample produced at a laser power of 2kW and scanning speed of 0.5m/sec was found to show the lowest percentage of wear volume and the sample produced at laser power of 1.4kW and scanning speed of 0.5m/sec had the lowest percentage of the coefficient of friction; and this outcome can be attributed to the martensitic structure formed during cooling. The results obtained showed that the poor wear behaviour of the titanium alloy has been improved with the addition of Ti-Mo into their lattices. The experimental results indicated that the corrosion rate of the developed composites decreased significantly with the addition of the Ti-Mo powder. The results obtained from the polarization behavior show a decrease in the polarization resistance. While the open-circuit potential (OCP) for the alloy was found to reduce with time due to oxide film thickening on the metal surface... , M.Ing. (Mechanical Engineering Science)
- Full Text:
Die isolering van Mo-99 uit klowingsmateriaal vir gebruik in 'n 99Mo/99mTc-generator
- Authors: Van der Walt, Tjaart Nicolaas
- Date: 2015-10-07
- Subjects: Radiochemistry , Radiopharmaceuticals , Molybdenum , Ion exchange chromatography , Nuclear medicine
- Type: Thesis
- Identifier: uj:14239 , http://hdl.handle.net/10210/14692
- Description: D.Sc. (Chemistry) , Please refer to full text to view abstract
- Full Text:
Hydrocracking of aromatic hydrocarbons over molybdenum based catalysts
- Authors: Foukaridis, George Nikiforos
- Date: 2014-05-19
- Subjects: Molybdenum , Catalysts , Catalysis
- Type: Thesis
- Identifier: uj:11108 , http://hdl.handle.net/10210/10696
- Description: M.Sc. (Chemistry) , Please refer to full text to view abstract
- Full Text:
Synthesis of tungsten and molybdenum promoted mesoporous metal oxides by inverse micelle approach for the evaluation of catalytic behavior on different reactions
- Authors: Hlatshwayo, Xolani Sibusiso
- Date: 2020
- Subjects: Tungsten , Molybdenum , Catalysis
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/473948 , uj:42703
- Description: Abstract: Tungsten and molybdenum promoted mesoporous metal oxides (ZrO2 and SiO2) were synthesized by inverse micelle method. Some of the as-synthesized bimetallic mesoporous catalysts were further converted to ternary mesoporous catalysts via deposition-precipitation whereby palladium nanoparticles were deposited or introduced in the system. The main objective of this investigation was to alterative hetero-catalyst for the modified homogeneous system of aminolysis of epoxides, acetylation of alcohols, and methoxycarbonylation of phenylacetylene by employing the as-synthesized Lewis acid catalysts. A variety of reactions such as aminolysis of epoxides, acetylation of alcohols and methoxycarbonylation of phenylacetylene were investigated. A total of six catalysts were fully characterized by BET, p-XRD, TPR, TPD, TGA, TEM, SEM, and EDX. Interestingly, the as-synthesized catalysts were active in the investigated reactions, with the promoted ones showing molybdenum promoted catalysts with greater activity than the tungsten. The binary mesoporous metal oxide catalysts were utilized for the aminolysis of epoxides, and the acetylation of alcohols, while the ternary mesoporous metal catalysts were employed in the investigation of methoxycarbonylation reaction. The advantage of these heterogenized systems is that the catalysts possess a higher potential of recyclability. , M.Sc. (Chemistry)
- Full Text: