Rhenium as a Hard Chrome Replacement for Gun Tubes
Guns have been used since early times to protect and invoke power. More research studies have been made on gun materials to improve its performance. There are also laws and environmental mandates that require the materials to be environmental friendly. The original article discusses hard chrome material that is used for gun tubes and rhenium as its alternative. It was discovered, with the use of metallurgical microscopes, that hard chrome does not follow the federal safety and environmental mandates and it reduces the optimum performance of the gun. Metallurgical microscopes have proved to be useful in the field of metallurgy. Studies looking for future metal products and materials base their results on findings of metal materials that were examined with metallurgical microscopes.
A coating of hard chrome on guns was the standard on old guns. This coating, however, gave the gun poor performance with today’s modern ammunition, does not satisfy environmental guidelines, and went beyond the heat treatment limit for gun barrels. A solution for this is the low-temperature deposition of rhenium coating in gun tubes. Rhenium, as a substitute has many properties that are advantageous as coating material for gun tubes. It is very ductile with increased tolerance for carbon and hydrogen, has the highest work hardening coefficient compared with other metals, and lastly has no brittle-to-ductile transformation. Aside from its properties, rhenium can be alloyed with other metal materials which reduce material cost.
A gun tube coating, according to the article, must have good adhesion between the coating and the gun tube steel. Two methods are being done to acquire this. One is to utilize low temperatures when performing the coating process. Another method is the addition of a diffusion barrier or a carbon getter at the gun interface. It is a great challenge to achieve sufficient coating adhesion during the coating process. It is more difficult to achieve this with low-temperature methods due to insufficient energy in supporting interdiffusion and bonding on the substrate and coating. Good adhesion in the gun tube environment would mean adhesion in the most intricate environments possible. The original article discusses this technical process in detail complete with magnified images taken from metallurgical microscopes.
The article concludes with judging rhenium as the best material choice for pure metallic gun tube coating. The article also discussed the best methods of coating a gun tube with rhenium lining.A low temperature means of applying rhenium coatings is using nonaqueous electrodeposition Rhenium coating is economically appealing with a performance demonstrated system. A good barrier to diffuse carbon and increase solid solubility between rhenium and steel is nickel. CVD chromium and cobalt can also be used as an interlayer with nickel and cobalt being nobler than steel. Materials that can be rhenium coated are copper, aluminum, magnesium, and polymers. Aside from metal materials, another option is ceramic materials but rhenium is still the best choice. Military and law enforcement agencies will profit from research studies being made on these materials for ammunition. More research is needed to gain additional knowledge and substitute materials for future use. Original article
