Carbon corrosion version

Intercrystalline corrosion was a serious problem with the austenitic stainless steels early in their development since carbon contents then were relatively high, e.g. En58J contained up to 0.12type stainless steel contained up to 0.08 Vo C. The problem in relation to surgical implants has been reported by Scales eta/. and as a result of this and several other reports the British, American and International Standards specified the use of a 316S12 type austenitic stainless steel which contains 0.03 Vo C max. The use of the lower carbon content stainless steels as specified in the various standards has now eliminated the problem of sensitisation of implants. If manufacturers do use the 0.08% C versions they have to be very careful with the forging temperatures or anneal the prostheses afterwards. 

Alloy 400 is known as Monel and its age-hardenable version is K-500. The corrosion resistance of alloy 400 is better than pure nickel in nonoxidizing mineral acids. The alloy shows poor corrosion resistance in HNO3, FeCl3, CuCl2, moist Cl2, chromic acid, S02 and NH3 shows corrosion resistance to HF in the absence of air at all temperatures and is susceptible to SCC in moist aerated HF and H2SiF6. Alloy 400 is unaffected by alkaline salt solutions such as chlorides, carbonates, sulfates and acetates. 

Based on the chemical composition, corrosion-resistant nickel-based alloys consist of commercially pure nickel. Ni-Cu alloys, Ni-Mo alloys, Ni-Cr-Mo alloys, and Ni-Cr-Fe alloys.63 The cast versions of the nickel-based alloys do not have the same corrosion resistance as the corresponding wrought products, mainly due to the higher carbon and silicon contents and the anisotropic microstructure of the cast products. (Rebak)5... 

Austenitic alloys also make use of the concept of stabilization. Stainless types 321 and 347 are versions of type 304 stabilized with titanium and niobium, respectively. These elements will preferentially combine with carbon that comes out of solid solution during weld solidification. Rather than a loss of corrosion resistance associated with formation of harmful chromium carbides, the carbides of titanium and niobium are not detrimental to corrosion resistance. The austenitic family of stainless also prompted another approach to avoiding the effects of chromium carbide precipitation. Because the amount of chromium that precipitated was proportional to the carbon content, lowering the carbon could prevent sensitization. Maintaining the carbon content to below about 0.035% vs. 

Weak organic acids are used because they tend to be inexpensive and less corrosive than the sulfuric or hydrochloric acids used in early versions of the process. The salts of weak acids such as carbonic, formic or acetic have proven to be effective [19]. 

Various versions of the hot potash process are today offered by a number of different licensors. Apart from measures intended to reduce heat demand, these versions differ by their additives to the potassium carbonate solution, which are in some cases intended to activate the reaction and in others to prevent corrosion. 

In this section we want to present data for binary coadsorption equilibria of gas mixtures on activated carbon (NORIT R 1) which have been taken by combined volumetric-gravimetric measurements. We start with a set of data which have been measured with the instrument depicted in Figs. 4.1,4.2. Then we describe in brief a new type of volumetric-gravimetric instrument including a magnetic suspension balance allowing also measurements with corrosive sorptive gases. Equilibria as well as kinetic data taken at this instrument will be presented. Finally we hint at a commerciahzed version of this instrument offered by BEE - Japan company. 

The version with circulating liquid electrolyte has the following advantages (1) it becomes much simpler to maintain the water balance in the cell, since there is no chance for the electrodes to dry out, and the electrolyte flow can be used to eliminate product water (2) the electrolyte flow can also be used to eliminate heat, so that special cooling plates or loops for a cooling fluid are not required (3) the electrolyte flow serves to level any gradients of electrolyte concentration that could arise within an individual cell or within the battery and (4) the electrolyte flow may serve to eliminate foreign matter (e.g gas bubbles, corrosion products, insoluble carbonates) that mrns up in the liquid. 

GDL, which can only indicate a loss of PTFE in this region. The opposite trend was observed on the electrode side of the cathode GDL, with an approximately 15% and an approximately 35% increase in the flnorine to graphite signal ratio for the US06 cycling and starl/stop cycling, respectively. These measurements are a strong indication of corrosion of the MPL carbon, as opposed to the case of the fibers of the version 2.22 anode GDL in contact with the flow field. 

The addition of 1% V to an Alloy B-type composition was first patented in 1959. The resultant commercial alloys, Corronel 220 and Hastelloy AUoy B-282 were found to be superior to Alloy B in resisting knifeline attack, but were not immune to it In fact, it was demonstrated that the addition of 2% V decreased the corrosion resistance of the base metal in HCl solntions. During this time, improvements in melting techniques led to the development of a low-carbon, low-iron version of Alloy B called Alloy B-2. This alloy did not exhibit any propensity to knifeline attack. 

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