Research
A Summary of six research in this page Is now available for reading. For More Researches or Continue reading of These essays please contact to dr@arman-sedghi.comThe effect of Graphitization on the Mechanical Properties of Two dimensional Carbon – Carbon Composites
Evolution of Novalak Resin as a Precursor For Fabrication of Carbon – Carbon Composites
The Effect of Precursor Content on the Structure and Properties of Two Dimensional Carbon – Carbon Composites
The Effect of Surface Treatments on Production SiC(w) form Rice Husks
The Relationship Between Microstructure and Electrochemical Behaviour of Mixed RuO2 – TiO2 Coatings on Titanium Substrate for Cl2 Production
Fabrication of Al-Pt Coating on Ni-Based Superalloys by Sputtering-Ion Beam Technique under Argon Plasma
The effect of Graphitization on the Mechanical Properties of Twodimensional Carbon – Carbon Composites
In this article the effect of graphitization in two dimensional c-c composite bodies prepared by impregnation of novalak resin is reported. Mechanical properties were determined by bending tests and microstructural features were studied by SEM and XRD.It was found that primary graphitization at 2300°C followed by graphitization at 2500°C improves the mechanical strength remarkable. Repeated graphitization and long-term treatment at 2500°C, however , found to have an adverse effect .Microstructural observations revealed that the level of strength is mainly controlled by a sheath developed around the fibre during graphitization.
Applying and improper thermal regime affects the matrix – fibre adherence and may cause the destruction of the fibres. This enhances the crack propagation and causes early failure of composite body under loading.
Evolution of Novalak Resin as a Precursor For Fabrication of Carbon – Carbon Composites
Part І.Optimization of curing stages
Curing of novalak resin has been investigated by applying different thermal analysis methods and solvent exteraction technique.
Result revealed theat cure can be optimized by finding the critical steps in cure and hold resin in these steps for appropriate time . Best result were also archieved by using resins which contained lower free phenol and hexamine amount.Application of pressure is necessary in initial stages of cure but found to be harmful in the final stages . It was also found that due to the defects produced in the final stages of curing, this process cannot be completed and long time post cure should be applied on these resin.By applying a special curing regime, it was proved that defects during pyrolysis stage could be decreased profoundly and a carbon residue of more than 67 percent expected.the results are explained by emphasis on carbon – carbon application.
The Effect of Precursor Content on the Strcture and Properties of Two Dimensional Carbon – Carbon Composites
In the fabrication of carbon – carbon composites by thermoset resin precursors, the amount of precursor resin is so important, but there is not enough information on the effect of this parameter on the properties of two-dimensional carbon – carbon composites during and after composite fabrication.
In this research, the effect of phenolic resin precursor on the structure and properties of two-dimensional carbon – carbon composites investigated during and after fabrication.In this respect, a model of resin distribution between carbon fibre layers proposed and effect of its variation during and after fabrication on microstructure and mechanical properties of two-dimensional carbon – carbon composites investigated.
The Effect of Surface Treatments on Production SiC (w) form Rice Husks
In this study two different batches of acid (H2SO4) and alkaline (NaOH) treated raw raice husks prepared.the materials were subjected to coking and pyrolysis for producing SiC under argon atmosphere.The effect of alkaline and acid treatments on qauntity and type of SiC (whiskers and particulates) via their effect on internal and external surfaces of rice husks were determined.
It was concluded that, silicon carbide whiskers (SiCw) growed over both internal and external surface of rice husks with a higher SiCw growth on external syrface due to presence of larg quantity of SiO2. It was also shown that use of alkaline treatment on rice husks resulted in disintegration of external surface and also the removal of free SiO2, whereas the use of acid treatment did not have any major effect on external or internal surface of rice husks therefore silica was unaffected. However, acid treatment resulted in decomposition of high molecular weight organic compounds to smaller molecules. The overall effect of alkaline and acid treatments on rice husks was a reduction and increase of resultant SiC, respectively.
The Relationship Between Microstructure and Electrochemical Behaviour of Mixed RuO2 – TiO2 Coatings on Titanium Substrate for Cl2 Production
RuO2 – TiO2 coatings because of very good corrosion resistance and electrochemical properties have been widely used in chlor – alkali industries.
In the present work, RuO2 – TiO2 coatings were produced by thermal decomposition from aqueous solutions of ruthenium and titanium chlorides in appropriate combination.
The electrochemical behaviours of coatings were assessed by electrochemical techniques such as cyclic voltammetry and polarisation measurements.
SEM micrographs of the electrodes show a cracked – mud morphology over the electrodes.Microscopic observation of the electrodes surfaces indicated deepening of cracks and pit formation on the surfaces by electrolysis.
The compactness uniformity of the coating improved as the RuO2 content increased. The increase in RuO2 content also decreased the over potential.
It is concluded that it is more beneficial to coat the used anodes for chlor.
Alkali industry for a cost saving purpose, while electrochemical behavioure doesn’t change.
Fabrication of Al-Pt Coating on Ni-Based Superalloys by Sputtering-Ion Beam Technique under Argon Plasma
Protective coatings are applied on the engineering materials to improve their physical, thermo chemical and mechanical properties. These coatings are used in various fields of industrial applications specially gas turbine blades, and in this respect, many research projects have been conducted to improve their properties. In the present study, the formation of Al-Pt (Aluminum/Platinum) alloy coatings on Nickel-based superalloys has been investigated. Sputtering ion beam technique under Argon plasma, pack cementation and subsequent heat treatment has been used to fabricate these coatings.
The main goal of this paper is to change the method for fabrication of platinum layer and investigate about effect of this variation on the morphology of coating. The results of this study confirm well with the results of other investigations, and its related to slow diffusion of platinum through coating. This method can produce uniform coatings faster and promise to be industrial technique for the fabrication of such coatings.