155:. When ammonia comes into contact with the heated work piece it dissociates into nitrogen and hydrogen. The nitrogen then diffuses onto the surface of the material creating a nitride layer. This process has existed for nearly a century, though only in the last few decades has there been a concentrated effort to investigate the thermodynamics and kinetics involved. Recent developments have led to a process that can be accurately controlled. The thickness and phase constitution of the resulting nitriding layers can be selected and the process optimized for the particular properties required.
20:
349:, 4300, 5100, 6100, 8600, 8700, 9300 and 9800 series, UK aircraft quality steel grades BS 4S 106, BS 3S 132, 905M39 (EN41B), stainless steels, some tool steels (H13 and P20 for example) and certain cast irons. Ideally, steels for nitriding should be in the hardened and tempered condition, requiring nitriding to take place at a lower temperature than the last tempering temperature. A fine-turned or ground surface finish is best. Minimal amounts of material should be removed post nitriding to preserve the surface hardness.
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the thermal stability of the plasma plant, since the heat added by the plasma is already present during the warm up and hence once the process temperature is reached the actual nitriding begins with minor heating changes. For the nitriding process hydrogen gas is also added to keep the surface clear of oxides. This effect can be observed by analysing the surface of the part under nitriding (see for instance).
388:
mind: the so-called nitriding steels. The reception in
America was less impressive. With so little demand the process was largely forgotten in the US. After WWII the process was reintroduced from Europe. Much research has taken place in recent decades to understand the thermodynamics and kinetics of the reactions involved.
250:
In plasma nitriding, the reactivity of the nitriding media is not due to the temperature but to the gas ionized state. In this technique intense electric fields are used to generate ionized molecules of the gas around the surface to be nitrided. Such highly active gas with ionized molecules is called
201:
salt. The salts used also donate carbon to the workpiece surface making salt bath a nitrocarburizing process. The temperature used is typical of all nitrocarburizing processes: 550 to 570 °C. Unfortunately, since the salts used are extremely toxic, modern environmental and safety regulation have
333:
are also used. Indeed, argon and hydrogen can be used before the nitriding process during the heating of the parts to clean the surfaces to be nitrided. This cleaning procedure effectively removes the oxide layer from surfaces and may remove fine layers of solvents that could remain. This also helps
387:
Systematic investigation into the effect of nitrogen on the surface properties of steel began in the 1920s. Investigation into gas nitriding began independently in both
Germany and America. The process was greeted with enthusiasm in Germany and several steel grades were developed with nitriding in
278:
Usually steels are beneficially treated with plasma nitriding. This process permits the close control of the nitrided microstructure, allowing nitriding with or without compound layer formation. Not only is the performance of metal parts enhanced, but working lifespans also increase, and so do the
313:
Since nitrogen ions are made available by ionization, differently from gas or salt bath, plasma nitriding efficiency does not depend on the temperature. Plasma nitriding can thus be performed in a broad temperature range, from 260 °C to more than 600 °C. For instance, at moderate
1319:
310:(PVD) process and labeled duplex treatment, with enhanced benefits. Many users prefer to have a plasma oxidation step combined at the last phase of processing to produce a smooth jetblack layer of oxides which is resistant to wear and corrosion.
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A plasma nitrided part is usually ready for use. It calls for no machining, or polishing or any other post-nitriding operations. Thus the process is user-friendly, saves energy since it works fastest, and causes little or no distortion.
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strength of the metals being treated. For instance, mechanical properties of austenitic stainless steel like resistance to wear can be significantly augmented and the surface hardness of tool steels can be doubled.
188:
Ammonia as nitriding medium – though not especially toxic it is harmful when inhaled at a high concentration. Also, care must be taken when heating in the presence of oxygen to reduce the risk of explosion
506:
Zagonel, L; Figueroa, C; Droppajr, R; Alvarez, F (2006). "Influence of the process temperature on the steel microstructure and hardening in pulsed plasma nitriding".
259:, since no spontaneous decomposition is needed (as is the case of nitriding with ammonia). There are hot plasmas typified by plasma jets used for metal cutting,
476:
Menthe, E; Bulak, A; Olfe, J; Zimmermann, A; Rie, KT (2000). "Improvement of the mechanical properties of austenitic stainless steel after plasma nitriding".
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Simple operation – The salt bath and workpieces are heated to the desired temperature, and the workpieces are submerged for a given period of time.
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Only one process possible with a particular salt type – since the nitrogen potential is set by the salt, only one type of process is possible.
182:
Reaction kinetics heavily influenced by surface condition – an oily surface or one contaminated with cutting fluids will deliver poor results
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560:
Zagonel, L; Figueroa, C; Alvarez, F (2005). "In situ photoemission electron spectroscopy study of nitrogen ion implanted AISI-H13 steel".
185:
Surface activation is sometimes required to treat steels with a high chromium content – compare sputtering during plasma nitriding
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Precise control of chemical potential of nitrogen in the nitriding atmosphere by controlling gas flow rate of nitrogen and oxygen
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Quick processing time – Usually in the order of 4 hours or so to achieve desired diffusion, where other methods take longer.
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Kunst, Helmut; Haase, Brigitte; Malloy, James C.; Wittel, Klaus; Nestler, Montia C. "Metals, Surface
Treatment".
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The salts used are highly toxic – Disposal is controlled by stringent environmental laws in western countries.
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Larisch, B; Brusky, U; Spies, HJ (1999). "Plasma nitriding of stainless steels at low temperatures".
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721:"MIL-S-6090A, Military Specification: Process for Steels Used In Aircraft Carburizing and Nitriding"
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All round nitriding effect (can be a disadvantage in some cases, compared with plasma nitriding)
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With modern computer control of the atmosphere the nitriding results can be closely controlled
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surface. These processes are most commonly used on low-alloy steels. They are also used on
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605:
Meka, S.R.; Chauhan, A.; Steiner, T.; Bischoff, E.; Ghosh, P.K.; Mittemeijer, E.J. (2015).
314:
temperatures (like 420 °C), stainless steels can be nitrided without the formation of
197:
In salt bath nitriding the nitrogen donating medium is a nitrogen-containing salt such as
123:
The processes are named after the medium used to donate. The three main methods used are:
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to escape Nazi persecution. After his death in late 1960s the process was acquired by
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607:"Generating duplex microstructures by nitriding; nitriding of iron based Fe–Mn alloy"
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Nitriding alloys are alloy steels with nitride-forming elements such as aluminum,
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This process was invented by
Bernhardt Berghaus of Germany who later settled in
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Large batch sizes possible – the limiting factor being furnace size and gas flow
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Cost – These regulations have increased the costs involved in using salt baths.
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precipitates and hence maintaining their corrosion resistance properties.
255:, naming the technique. The gas used for plasma nitriding is usually pure
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379:), known to be associated with strongly enhanced mechanical properties.
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247:, is an industrial surface hardening treatment for metallic materials.
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ECM USA, Vacuum
Furnace Manufacturer: FNC Ferritic Nitrocarburizing.
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864:
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ECM USA, Vacuum
Furnace Manufacturer: Vacuum Purged Gas Nitriding.
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Heat treatment of ferrous materials: nitriding and nitrocarburising
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or spraying. There are also cold plasmas, usually generated inside
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https://www.ecm-usa.com/applications/ferritic-nitrocarburizing-fnc
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Relatively low equipment cost – especially compared with plasma
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In gas nitriding the donor is a nitrogen-rich gas, usually
65:
604:
325:) is usually the nitrogen carrying gas. Other gasses like
668:
Advanced
Thermally Assisted Surface Engineering Processes
475:
158:
The advantages of gas nitriding over other variants are:
359:
In 2015, nitriding was used to generate a unique duplex
464:
Ion
Nitriding and Nitrocarburizing of Sintered PM Parts
665:
Chattopadhyay, Ramnarayan (2004). "Plasma
Nitriding".
559:
641:
532:
436:
321:In the plasma nitriding processes, nitrogen gas (N
692:Practical Nitriding and Ferritic Nitrocarburizing
650:] (in German) (2nd ed.). Expert-Verlag.
342:Examples of easily nitridable steels include the
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757:https://www.ecm-usa.com/applications/nitriding
440:Ullmann's Encyclopedia of Industrial Chemistry
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202:caused this process to fall out of favor.
622:
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501:
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306:Plasma nitriding is often coupled with a
151:), which is why it is sometimes known as
16:Nitrogen diffusion case-hardening process
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178:The disadvantages of gas nitriding are:
18:
23:A modern computerised nitriding furnace
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205:The advantages of salt nitriding are:
192:
771:
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725:United States Department of Defense
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230:
13:
635:
14:
1375:
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642:Chatterjee-Fischer, Ruth (1995).
553:
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611:Materials Science and Technology
235:Plasma nitriding, also known as
138:
1317:
562:Surface and Coatings Technology
535:Surface and Coatings Technology
508:Surface and Coatings Technology
478:Surface and Coatings Technology
1311:
624:10.1179/1743284715Y.0000000098
584:10.1016/j.surfcoat.2004.10.126
520:10.1016/j.surfcoat.2005.11.137
457:
430:
1:
815:History of ferrous metallurgy
671:. Berlin: Springer. pp.
547:10.1016/S0257-8972(99)00084-5
490:10.1016/S0257-8972(00)00930-0
423:
64:Typical applications include
1320:"The Heat Treatment Library"
1058:Argon oxygen decarburization
744:An Introduction to Nitriding
727:. 7 Jun 1971. Archived from
363:in an iron-manganese alloy (
118:
7:
1219:Differential heat treatment
391:
356:, molybdenum and titanium.
10:
1380:
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303:and popularized globally.
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1143:Ferritic nitrocarburizing
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413:Ferritic nitrocarburizing
308:physical vapor deposition
1234:Post weld heat treatment
245:glow-discharge nitriding
820:List of steel producers
443:. Weinheim: Wiley-VCH.
338:Materials for nitriding
216:The disadvantages are:
1048:Electro-slag remelting
41:into the surface of a
24:
1354:Metal heat treatments
1258:Production by country
22:
1244:Superplastic forming
1163:Quench polish quench
1053:Vacuum arc remelting
1032:Basic oxygen process
1027:Electric arc furnace
241:plasma ion nitriding
1199:Cryogenic treatment
1022:Open hearth furnace
1010:Primary (Post-1850)
1001:Cementation process
888:Direct reduced iron
690:Pye, David (2003).
193:Salt bath nitriding
129:salt bath nitriding
970:Primary (Pre-1850)
749:2011-12-15 at the
25:
1359:Plasma processing
1304:
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932:Induction furnace
731:on 29 August 2019
696:ASM International
466:, October 7, 2004
418:Surface finishing
271:chambers, at low
153:ammonia nitriding
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1326:. Archived from
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1017:Bessemer process
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231:Plasma nitriding
133:plasma nitriding
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617:(9): 883–889.
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34:process that
33:
32:heat treating
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1332:. Retrieved
1328:the original
1323:
1318:Pye, David.
1313:
1306:
1186:Martempering
1181:Austempering
1152:
1090:Low hydrogen
908:Finery forge
904:Wrought iron
733:. Retrieved
729:the original
691:
667:
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514:(1–2): 452.
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104:components,
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45:to create a
27:
26:
1229:Forming gas
1133:Carburizing
990:Wootz steel
956:Steelmaking
855:sponge iron
568:(7): 2566.
541:: 205–211.
90:die-casting
70:crankshafts
1348:Categories
1334:2017-01-10
1286:Luxembourg
1266:Bangladesh
1208:Deflashing
1118:Ausforming
961:Steel mill
871:Cold blast
863:(produces
853:(produces
805:production
575:1712.01483
484:(1): 259.
424:References
365:martensite
59:molybdenum
1324:pye-d.com
1239:Quenching
1213:Hardening
1203:Deburring
1173:Tempering
1153:Nitriding
1148:Induction
1138:Cryogenic
1105:Hardening
1082:Annealing
1041:Secondary
924:Cast iron
897:Secondary
876:Hot blast
833:Ironworks
592:119102526
373:austenite
369:austenite
275:regimes.
119:Processes
106:injectors
98:extrusion
74:camshafts
55:aluminium
28:Nitriding
1364:Nitrogen
1123:Boriding
915:Puddling
865:pig iron
851:Bloomery
843:Smelting
747:Archived
398:Boriding
392:See also
354:chromium
327:hydrogen
273:pressure
265:cladding
257:nitrogen
88:screws,
86:extruder
51:titanium
39:nitrogen
36:diffuses
1291:Nigeria
1074:methods
918:Furnace
735:20 June
383:History
377:ferrite
285:fatigue
261:welding
199:cyanide
145:ammonia
115:tools.
110:plastic
102:firearm
94:forging
92:tools,
84:parts,
702:
679:
654:
590:
447:
297:Zurich
281:strain
269:vacuum
253:plasma
131:, and
100:dies,
96:dies,
1281:Italy
1276:India
1271:China
926:(via
906:(via
803:steel
675:–94.
646:[
588:S2CID
570:arXiv
331:argon
82:valve
66:gears
43:metal
30:is a
910:or
801:and
799:Iron
737:2012
700:ISBN
677:ISBN
652:ISBN
445:ISBN
347:4100
113:mold
108:and
57:and
930:or
619:doi
580:doi
566:200
543:doi
539:116
516:doi
512:201
486:doi
482:133
344:SAE
329:or
243:or
147:(NH
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1107:/
988:,
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698:.
694:.
673:90
615:32
613:.
609:.
586:.
578:.
564:.
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371:,
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708:.
685:.
660:.
627:.
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594:.
582::
572::
549:.
545::
522:.
518::
492:.
488::
453:.
375:-
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323:2
149:3
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