Stainless steels nitriding

A1 alloy, Ti, nitrided Ni and Fe alloys, coated stainless steel (nitride, proprietary), and stainless steel bipolar plate surfaces, decreasing electronic conductivity... 

Gruetzner, G., Sensitising a Cr-Ni-N2 Austenitic Stainless Steel to Intergranular Corrosion by Dichromium Nitride Precipitation , Cent. Doc. Siderurg, Circ. Inform. Tech., 30, 1165... 

Chromium iron manganese brown spinel, formula and DCMA number, 7 348t Chromium iron nickel black spinel, formula and DCMA number, 7 348t Chromium isotopes, 6 476 Chromium magnesium oxide, 5 583 Chromium manganese zinc brown spinel, formula and DCMA number, 7 348t Chromium-nickel alloys, 77 100-101 Chromium-nickel-iron alloys, 17 102-103 Chromium-nickel stainless steels, 15 563 Chromium niobium titanium buff rutile, formula and DCMA number, 7 347t Chromium(III) nitrate, 6 533 Chromium nitride, 4 668... 

Gcfv minding creates a diffused nitrogen (nitrogen compounds) case. Base metals arc alloy steels, nitriding steels, and stainless steels. Process temperature range is 480-590r C <900-1100 F). 

In addition, flame propagation is not possible in stainless-steel channels owing to the high heat conductivity and affinity to radicals. But even for materials which do not adsorb radicals, a minimum channel width exists below which no homogeneous combustion is possible any longer. Insulating materials such as silicon nitride and inert layers such as alumina are required to maintain the homogeneous reaction. 

As pointed out above, stainless steel is of primary interest for the near term large Tokamaks. Little work has been done on the nitriding of stainless steel by this method so far. Measurements performed by the Zurich group192) revealed that the reaction rates are an order of magnitude higher than those for titanium at 600 °C (see Table 5). However, nitrided steel is unstable under exposure to hydrogen plasma194 ). 

Similar measurements were also performed on stainless steel. The nitride layer was attacked by the hydrogen discharge and therefore no quantitative data on the hydrogen diffusion could be obtained192,194a). This system also requires further investigation. 

Care has to be taken in selecting materials for the die and punches. Metals are of little use above 1000 °C because they become ductile, and the die bulges under pressure so that the compact can only be extracted by destroying the die. However, zinc sulphide (an infrared-transparent material) has been hot pressed at 700 °C in stainless steel moulds. Special alloys, mostly based on molybdenum, can be used up to 1000 °C at pressures of about 80 MPa (5 ton in-2). Alumina, silicon carbide and silicon nitride can be used up to about 1400 °C at similar pressures and are widely applied in the production of transparent electro-optical ceramics based on lead lanthanum zirconate as discussed in Section 8.2.1. 

Abstract. The thin-film protective coat of titanium nitride (TiN) plotted to stainless steel (brand 12X18H10T) is explored. The mathematical model and methods of parametric identification are described. Kinetic parameters of hydrogen permeability through stainless steel membrane with TiN protective coat are determined. 

The investigated samples were stainless steel (12X18H10T) membranes with diameter 40 mm and thickness 0.2 mm. Some part of samples was covered by thin titanium nitride film plotted by vacuum ion-plasma sputtering. The typical thickness of the covering was 10 micrometers. Stehiometry of thin-film coats was explored by x-ray analysis method and turned out to be close to ideal. 

The samples without defensive film coat were studied by the method of concentration pulses (MCP) at pressure 0.2 Torr within the range of temperatures 370 -596 °C in order to determine the hydrogen permeability parameters of stainless steel (12X18H10T). The knowledge of these parameters allowed to simplify the problem of parameter identification for titanium nitride. The samples with titanium nitride covering were studied by method of permeability at pressures 0.5-249 Torr and the temperatures 380-670 °C. 

TABLE 3. The identification results of some experimental data for stainless steel (12X18H10T) covered by thin-film from titanium nitride... 

FIGURE 30 (A) Schematic representation of the boron nitride sample holder positioned inside the furnace and stainless steel body according... 

Girardon et al. (2005) discussed a transmission XAFS spectroscopy cell that is compatible with characterization of catalysts in the working state and with online analysis of reaction products. The cell consists of several plates of stainless steel and boron nitride linked together with graphite seals. The catalyst powder is held in a recessed channel in a central boron nitride plate. The cell is heated with cartridge heaters, and the thermocouple is placed in a channel in the central boron nitride block close to the catalyst bed. Gas flow is through the catalyst bed from top to bottom. The volume of this bed (0.45 cm3) is fixed by the dimensions of the recessed channel in the boron nitride plate—but it can be adjusted by having several different plates of different dimensions. The authors claimed that the cell is leak free and operational at temperatures up to 623 K in O2 and 673 K in H2, all at atmospheric pressure. 

In operation containers constructed of microwave-transparent materials, (e.g. quartz or fluoropolymers), are used to hold multiple samples inside the ultraCLAVE . The interior of the stainless steel vessel is protected by a titanium nitride or multi-layer PTFE plasma coating for complete acid and chemical resistance. Sample containers may be open or covered by a lid. After the samples are loaded (manually or robotically) the ultraCLAVE cover is lowered into place by an electric motor controlled from the system s PC. The vessel closure is engaged and secured in place to seal the ultraCLAVE for high pressure operation. 

Zirconium metal (mp 1855°C 15°C), like titanium, is hard and corrosion resistant, resembling stainless steel in appearance. It is made by the Kroll process (Section 17-A-l). Hafnium metal (mp 2222°C 30°C) is similar. Like titanium, these metals are fairly resistant to acids, and they are best dissolved in HF where the formation of anionic fluoro complexes is important in the stabilization of the solutions. Zirconium will burn in air at high temperatures, reacting more rapidly with nitrogen than with oxygen, to give a mixture of nitride, oxide, and oxide nitride (Zr2ON2). 

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