Basic features:
- The furnace atmosphere includes ionized ammonia produced by means of the Oxycan-a catalytic element. This significantly suppresses the diffusion mechanism of chemical reactivity and increases the share of solid solution diffusion in nitrogen transfer from gaseous medium into iron (steel).
- New idea of the nitrogen potential concept. The potential is compared to the nitrogen content in a steel sample upon its full saturation in the corresponding atmosphere at a fixed temperature and fixed oxygen content. Direct method of nitrogen potential determination is foil test. An oxygen probe Oxynip is used for indirect evaluation of the nitrogen potential and real-time process control. High process stability under actual working conditions.
| 
|  | | CGN 6.9/7 | CGN 8.26/7 | A number of CGN technological processes has been developed for the recent 10 years:
- High speed CGN.
- Corrosion-preventive CGN.
- CGN quenching.
- CGN of accessories for pressing (of stamp steels)
- CGN of powder materials.
- CGN of high-speed steels.
- CGN of stainless steels.
- CGN of titanium alloys.
 | Correlation between the oxygen sensor Oxynip feedback and nitrogen content in foil. Gas nitriding in atmosphere of a new atmosphere |
CGN of accessories for pressing (of stamp steels)
CGN of powder materials
| 1%С+25% Сu, Fe etc.
Parts of a drill pump.
All grains have carbonitriding edging without porosity |
High-speed CGN, 42CrMoV9
 | 1 - ⇒ - CGN 550оС, 24 h
2 - ⇒ - Traditional gas nitriding, 550oС, 24h |
CGN of titanium alloys
| 1 - ⇒ - КГА 680oС 2 - ⇒ - Вакуум, 850oС | CGN microstructure – Ti2N on the surface |
Comparative parameters of traditional nitriding and catalytic gas nitriding | Quality | Process parameters, workpieces properties | Traditional processes | Catalytic gas nitriding | | steel 41CrAlMo7 | Time of producing a layer within 0,2...0,3 mm thick, h | 24 | 12 | | Time of producing a layer within 0,7...0,8 mm thick, h | 75 | 48 | | Lifetime of gears of highly loaded reducers | 1,0 | 3,5 | | steel 42CrMo4V | Thickness of effective layer formed during the isothermal soaking 48 h, mm | 0,4 | 0,8 | | Fatigue strength of heavy track diesel crankshaft | 1,0 | 7,0 | | steel X38CrMoV 5 1 | Thickness of effective layer formed during the isothermal soaking 12 h, mm | 0,12 | 0,25 | | Lifetime of aluminum extrusion dies, tons of products | 3-6 | up to 20 |
Design of the CGN furnace:
The nitriding process is carried out in a welded heat-resistant leakproof retort suspended in the furnace. The furnace lining is made of light-weight chamotte bricks and fibrous thermal insulation. The upper butt of the retort is shut with a lined cover driven hydraulically. The tightness of the contact zone between the retort and cover is achieved by using two sealing cords. Nipples for seeping gas and supply of technological gases are provided in the cover. The oxygen probe and Oxycan-a catalytic element are also mounted in the cover. A fan ensuring stirring of the atmosphere inside the retort is fixed on the cover. Zigzag-type heating elements are made of Kanthal wire.  NPCS CGN control system: 1 – bombs with NH3 and N2 gases; 2 – nitriding process control system (NPCS CGN or semi-automated control); 3 – CGN furnace; 4 – charge cooling system; 5 – system of wasted gas aftertreatment
JSC Nakal – Industrial Furnaces delivers equipment on the turnkey basis.
The scope of delivery includes:
1. “Nakal CGN” CGN furnace. 2. Control cabinet, fully automated NPCS CGN system or semi-automated control of nitriding process. 3. Charge cooling system. 4. Optional system of wasted gas aftertreatment. 5. System for supplying technological gases fully automated in the NPCS CGN system. 6. Technological adjustment in nitriding process for the customer’s workpieces using the delivered equipment in accordance with the agreed technical requirements.
|
