NH3 Gas Effect of Gaseous Heat Treatment on some Properties Of Spreading (Diffusion) Surface Layer of Steel 20

We have studied in this paper the effect of thermal gaseous using NH3 – gas at some diffusion layers properties of tool steel 20 in temperature range (550 ,650 ,750, 850) 0C , 4h at each one . The purpose of this heat treatment is to get and determine the microhardness, fatigue and corrosion resistance. The micro-hardness was determined using Vickers's tester with values ranged between ( 130-435 ) HV. In order to verify these results, we studied the microstructure if the surface layers using metallurgical microscope and SEM (Scanning Electron Microscope). Furthermore the corrosion resistance was studied after immersing it in sea water for two year.

Effectiveness of the diffusion chrome coating on the mechanical and chemical properties of low-carbon steel

In this research, has been studied the spread of chromium atoms mechanism, and mechanical and chemical and properties of the diffusion chrome coating layer in low carbon steel, which is considered one of the surface treatment techniques. Where many practical experiences were carried out in the powdery saturation milieu to form a diffusion coating layer containing atomic chromium who will spread inside the painted surface, and has studied some mechanical and chemical properties after doing diffusion chrome coating. The tests results showed that the tensile strength and micro hardness and chemical corrosion resistance improved after the diffusion chrome coating, also increased the depth of coating layer By increasing the retention time in the oven and temperature, where this relationship is reflected with curve of the second degree. Conversely ductility decreased. Search results confirm the possibility of using diffusion chrome coating as a promising treatment in raising the efficiency of machinery elements that prone to oxidation or chemical corrosion in different temperatures.

Using New Chemical Materials as Coating Layers for Minimizing Friction and Wear

This study deals with the friction and wear behavior of coating layers (fluoride and Graphite).The coatings are thermally sprayed on cast iron disks. Sliding is performed between cylindrical pins manufactured from organic brake linings and the coated and uncoated disks. The coatings are characterized by measuring their hardness, porosity, and corrosion resistance. The corrosion resistance of the coating is tested by exposure to Nacl for 150 hours; the coating layer has had the best corrosion resistance. The friction and wear tests are conducted under contact pressures of (1.5 MPa to 7 MPa) and sliding speeds of 1 and 3 m/sec.