الفهرس 
Introduction and Literature ReviewOnly 14 pages are availabe for public view
Abstract
This study focused on preparation and characterization of chromium carbides and vanadium carbides as a types of transition metal carbides and used as coating to steel protection and in electrochemistry application.
Chapter one:
General introduction and literature review on transition metal compounds as (carbides & nitrides) and uses in several application in coatings for metal protection
Chapter two:
Systematic experiments were done in the autoclave to obtain
chromium carbide and vanadium carbide nanoparticles from Cr2O3 and V2O5 powders, respectively by single step thermo-chemical method at relatively low temperature 800 °C for 20 h. Because of the high thermal stability and its unique properties, Cr3C2 & V8C7 can be used as a potential material for various industrial application, this nanopowders was characterized by XRD, SEM/EDX and HR-TEM to measure the particle size and morphology, the particle size for two types of TMC was in range 30 – 70 nano. The Cr3C2 exhibits a superior specific capacitance of 171.6 F g-1 at a current density of 1 A g-1, The V8C7 exhibits a specific capacitance of 83.33 F g-1 at a current density of 1 A g-1.
Chapter three:
The chromium carbides coatings were formed on the surface of AISI O2 cold work tool steel via pack cementation process at different temperature (900, 1000, 1100 °C) and different holding time (4, 6, 8 h) for each temperature. One layer formed at 900 °C was mainly Cr7C3 phase, two layers formed at 1000 and 1100 °C, the outer 2nd layer was mainly Cr23C6 phase, the inner 1st layer was mainly Cr7C3 phase, all layer’s thickness increases with increasing time and temperature from 8 – 50 µm. The microhardness of chromium carbides coatings was 1380 – 1500 HV0.05 (13.5 – 14.7 GPa) at Cr23C6 layer, 1670 – 1790 HV0.05 (16.4 – 17.5 GPa) at Cr7C3 layer. The Arrhenius equation is used to study the kinetics of chromium carbide coating growth. The activation energy for the process is 187 kJ/mol. The variation in chromium carbide coatings thickness (d) with holding time (t) and treatment temperature (T) can be expressed as follows:
d =
Chapter 4:
Hard coatings of vanadium carbide can be produced via the Thermo-reactive diffusion TRD technique on AISI D3 steel. The TRD process produces coatings with a defined, continuous, dense, and homogenous interface at temperatures 1000° C after 4 h of treatment with layer thicknesses equal 13 microns and its microhardness of this layer was 2300 HV closed to VC phases. Carbide compounds that are formed are vanadium carbides phases (VC, V4C3, V6C5, V2C) and chromium carbides phases.
Hard coatings of vanadium carbide deposited on D3 tool steel exhibit better electrochemical behavior than the substrate, shown in the higher values of corrosion potential and lower values of interchange current for the coating, the results showed that the corrosion potential of the substrate was an average -506 mV and for the coating -370 mV, due to its ceramic composition and chemical stability, and can be used as a protective layer on steel used for fabricating cutting tools.