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During the daily production process, due to the aging of the sintering furnace, nitrogen generator, ammonia decomposition and other equipment, the powder metallurgy products after the furnace have a series of oxidation problems such as blackening, yellowing, decarburization, and sandblasting on the surface of the product.

After the problem occurs, the manufacturer should investigate the protective atmosphere as soon as possible. The inspection items generally include whether the regular maintenance of the nitrogen generator is carried out normally, the working status of the nitrogen generator, and whether the values of the nitrogen generator P860 nitrogen analyzer are accurate. Whether the working pressure of the adsorption tower of the nitrogen generator is below the standard line, whether the deoxygenation temperature of the palladium catalyst in the hydrogenation and deoxygenation part is outside the normal range, whether the nitrogen purification and drying part is heated normally, and the oxygen content and nitrogen moisture at the rear end of the nitrogen purification are indicators Whether it is within the range of the standard value, it is necessary to take a timely response to the respective problems.

Powder metallurgy products usually use mesh belt continuous annealing furnace and push rod annealing furnace for sintering. The protective atmosphere is divided into copper-based products and iron-based products according to the materials of powder metallurgy products. Normally, iron powder is pressed to form the most sintered products, and iron-based For powder metallurgy products, high-purity nitrogen with a water content of less than 5PPM and a high-purity 99.999% produced by an ammonia decomposition hydrogen production device or a PSA on-site nitrogen generator and hydrogenation and deoxygenation purification can be used as a protective atmosphere. After some oxidation problems occur in powder metallurgy products, check that the nitrogen generator and ammonia decomposition furnace are all normal, or after troubleshooting of the nitrogen generator and ammonia decomposition, the oxidation problem of powder metallurgy products still exists.

The next step should consider the sintering furnace itself.

Whether it is a push rod furnace or a mesh belt furnace, there will be a water jacket cooling zone. After the muffle tube of the sintering furnace is aged, there will be water leakage. The water will decompose into oxygen at high temperature, causing the powder metallurgy products to become black and yellow and decarbonize. Ding Wentao, if Burn through at high temperatures and flames. The flames are caused by the combustion of hydrogen and powder metallurgical components in the sintering furnace. At this time, sandblasted objects will be produced on the surface of the product, which are combustion residues. If a protective cover is used to cover it, it will be Improved, but the high-purity nitrogen protection is not in place will cause slight oxidation.

However, for pure copper-based powder metallurgy products, only the 75% hydrogen + 25% nitrogen mixed gas produced by ammonia decomposition to produce hydrogen can be used as the protective atmosphere. Of course, the use of high-purity hydrogen is more effective, due to the large gas cost and operational safety. Most of them use ammonia decomposition hydrogen production equipment as a source of hydrogen.

When the muffle tube of the sintering furnace leaks and burns through, the production of the muffle tube should be stopped immediately and replaced. So as not to affect the quality of the product!