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gas dissociation

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Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.pnfn.t65900111
EISBN: 978-1-62708-350-8
... and oxynitriding processes in the fluidized-bed furnace. It also explains how to operate the fluid bed for nitriding. The chapter provides a discussion on the measurement of the gas dissociation. fluidized-bed furnaces gas dissociation gas nitriding oxynitriding A FLUIDIZED-BED FURNACE SYSTEM can...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.pnfn.t65900039
EISBN: 978-1-62708-350-8
... the processes involved in controlling temperature, gas dissociation, oxygen probes, and nitriding sensors. ammonia control systems design criteria furnace equipment nitriding nitriding sensors THE NITRIDING FURNACE is simple in design. Other than the materials used, little has changed in furnace...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.pnfn.t65900023
EISBN: 978-1-62708-350-8
... Abstract Several process parameters must be considered to ensure success in achieving desired metallurgical properties and to minimize distortion. This chapter provides a detailed discussion on the liberation of nitrogen, dissociation of the gas at the selected nitriding temperature, why...
Image
Published: 01 December 2003
Fig. 1 Simple schematic arrangement of an ammonia gas nitriding system. A, bulk storage tank; B, gas nitriding furnace; C, gas dissociation test station; D, exhaust to atmosphere. Source: Pye Metallurgical Consulting Inc. More
Image
Published: 01 December 2003
Fig. 2 Schematic of interstitial diffusion during the nitriding process. The work is heated to the nitriding temperature with ammonia flowing into the retort. The ammonia gas dissociates to nitrogen and hydrogen at the part surface. The nitrogen diffuses into the work in atomic form More
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.pnfn.t65900185
EISBN: 978-1-62708-350-8
... is contaminated with a cutting fluid that is chlorideor sulfide-based, then serious surface pitting and loss of hardness may result. It can be safely said that any grease or acidic compound on the surface of a steel is very likely to cause nitriding problems. Loss of Gas Dissociation When gas dissociation...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.pnfn.t65900031
EISBN: 978-1-62708-350-8
... implies, the process developed by Dr. Carl Floe in 1942 (see Chapter 1 and Ref 5 ) involves a two-step procedure: one step at the normal nitriding temperature (500 °C, or 930 °F) with normal ammonia gas dissociation (between 15 and 30%), and a second step at a higher temperature between 540 and 565 °C...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.pnfn.t65900013
EISBN: 978-1-62708-350-8
... diffuse. The higher the temperature to which the steel is elevated, the faster and deeper the nitrogen diffusion occurs. However, caution must be exercised in relation to: Temperature selection Gas dissociation Surface area of treated work Steel chemistry Quality and type of formed case...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.pnfn.t65900245
EISBN: 978-1-62708-350-8
... limits and adjust accordingly. Check also that the gas dissociation and gas ratios are within the required operating limits and that the process temperature is correct. Lastly, check that the plasma conditions are correctly set in terms of power density, voltage, amperage, pressure, gas ratios...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.pnfn.t65900001
EISBN: 978-1-62708-350-8
... at a temperature of about 500 °C (930 °F) with 15 to 30% dissociation of the ammonia (i.e., an atmosphere that contains 70 to 85% ammonia). This will produce the nitrogen-rich compound at the surface. Once the cycle is complete, the furnace temperature is increased to approximately 560 °C (1030 °F), with gas...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.pnfn.t65900139
EISBN: 978-1-62708-350-8
... control analysis mass spectrometry photo spectrometry plasma nitriding sputtering PROCESS GAS CONTROL for plasma (ion) nitriding is a matter of estimating the flows necessary to accomplish the required surface metallurgy. Conventional gas nitriding systems measure the dissociation of the ammonia...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2000
DOI: 10.31399/asm.tb.htgpge.t67320133
EISBN: 978-1-62708-347-8
... Abstract Nitriding is a case-hardening process used for alloy steel gears and is quite similar to case carburizing. Nitriding of gears can be done in either a gas or liquid medium containing nitrogen. This chapter discusses the processes involved in gas nitriding. It reviews the effects...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 September 2005
DOI: 10.31399/asm.tb.gmpm.t51250227
EISBN: 978-1-62708-345-4
...—including nitrogen, previously dissociated ammonia, hydrogen, argon, and oxygen—are added in a controlled way to conventional ammonia. The effect of these additions, with the exception of argon, is to reduce the nitriding potential of the atmosphere; argon has no effect on N p . Controlled gas nitriding...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 July 1997
DOI: 10.31399/asm.tb.wip.t65930197
EISBN: 978-1-62708-359-1
... in a state of supersaturation in the martensite. The presence of hydrogen in a weld is generally due to moisture that is introduced in the shielding gas, dissociated by the arc to form elemental hydrogen, and dissolved by the molten weld puddle and by the adjacent region in the HAZ. In the supersaturated...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 December 2003
DOI: 10.31399/asm.tb.pnfn.t65900065
EISBN: 978-1-62708-350-8
... ammonia gas with a dissociation of approximately 30% at 495 °C (925 °F). This is followed by raising the temperature during the last third of the cycle to 565 °C (1050 °F) with a dissociation rate of 75 to 80%. In some applications, formation of the surface compound zone is desirable. If the layer...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 June 2007
DOI: 10.31399/asm.tb.pmsspmp.t52000059
EISBN: 978-1-62708-312-6
... in the 1980s, as a result of increasing demands on magnetic and corrosion-resistance properties. Although some sintering furnaces for carbon steel parts now have gas quench capability in their cooling zones, permitting so-called sinter hardening, most industrial furnaces for stainless steels presently lack...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 March 2006
DOI: 10.31399/asm.tb.pht2.t51440141
EISBN: 978-1-62708-262-4
... in the atmosphere dissociates to form nascent nitrogen at the work surface, and the nascent nitrogen diffuses into the steel simultaneously with carbon. Typically, carbonitriding is carried out at a lower temperature and for a shorter time than gas carburizing, in order to obtain a total case depth of about 0.8 mm...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 November 2007
DOI: 10.31399/asm.tb.htcma.t52080067
EISBN: 978-1-62708-304-1
... containing both aluminum and titanium are strengthened by γ′ phase, Ni 3 (Al,Ti). For these alloys, nitridation by forming internal nitrides of aluminum and titanium can deplete the surface layer with aluminum and titanium, thus weakening the alloy. Under a high-velocity combustion gas stream with severe...
Book Chapter

Series: ASM Technical Books
Publisher: ASM International
Published: 01 June 2007
DOI: 10.31399/asm.tb.pmsspmp.t52000167
EISBN: 978-1-62708-312-6
... of PM stainless steels was not practiced to any great extent until the introduction of PM stainless steel exhaust flanges and hot exhaust gas outlet (HEGO) bosses in the early 1990s. Therefore, most publications addressing welding of PM stainless steels are of relatively recent origin. The metallurgical...
Series: ASM Technical Books
Publisher: ASM International
Published: 01 June 2008
DOI: 10.31399/asm.tb.emea.t52240395
EISBN: 978-1-62708-251-8
... for obtaining the required higher second-stage dissociation. Fig. 21.9 Effect of one- and two-stage nitriding on white layer. (a) Single stage, gas nitrided for 24 h at 525 °C (975 °F). (b) Double stage, gas nitrided for 5 h at 525 °C (975 °F) followed by second stage at 565 °C (1050 °F) for 24 h...