Corrosion response

Dermal/Ocular Effects. Because BCME is highly reactive, it is directly irritating to skin and other epithelial tissues. Chronic (lifetime) application of BCME (1 mg/dose) to the skin of mice produced a strong corrosive response, including hair loss, hemorrhagic rash and edema of subcutaneous tissue (Van Duuren et al. 1968). In rabbits, a single application of undiluted BCME lead to moderate erythema and marked necrosis, and a primary dermal irritation score of 6 was assigned (Union Carbide 1968). A dose of 5 / L (7 mg) applied to the eye of rabbits produced severe corneal necrosis (Union Carbide 1968). 

The importance of MP can be related to the physical state of the substance under the conditions of Draize test. In this study, it was assumed that chemicals with a MP less than or equal to 37°C would exist as liquids in the test procedure and that, in general, liquids would be more likely than solids to cause corrosion and irritation. The results confirm that there is indeed a relationship between physical state and the potential for acute skin toxicity. The fact that some solids are corrosive or irritant may relate to the fact that their MPs are not much higher than 37°C and that they exist as wax-like substances, which are more capable of penetrating into the skin than are solids with higher MPs. For example, carvacrol, and thymol, which are both irritant and corrosive, have predicted MPs of 38°C and 38.1°C, respectively. In the case of other solids, such as benzene sulfonyl chloride (MP = 61°C), the corrosive response may be due to a more toxic derivative (e.g., benzene sulfonic acid). 

Johnson PE, Bernstein JJ, Hunter G, Dawson WW and Hench LL (1977) An in vitro and in vivo analysis of anodized tantalum capacitive electrodes corrosion response, physiology, and histology. J Biomed Mater Res 11 637-656. 

We believe that the definition of this test is a prerequisite to rationalization of atmospheric corrosion responses. 

Corrosion Response. The responses of metals to this test have been measured by several methods. A brief survey which follows forms a self-consistent basis of some generalizations on atmospheric corrosion. Unless stated otherwise, the examples will be of the corrosion of an alloy Ni8oFe20 ... 

Van Orden, A. 1985. Corrosive response of the interface tissue to 316L stainless steel, Ti-based alloy and cobalt-based alloys. In The Dental Implant, R. McKinney and J.E. Lemons (Eds.), pp. 1-25, Littleton, PSG. 

The corrosion response within the human body is of most interest in this field. However, direct electrochemical testing in humans ranges from difficult (in the mouth) [i], to virtually impossible (for orthopaedic devices for example) because of ethical, safety, legal, and regulatory considerations. Consequently, much effort has been devoted to identifying alternative environments which, to a greater (or lesser) degree, simulate the corrosion conditions in vivo in humans. 

Fraker, A. C., Van Orden, A. C., Sung, P., and Hahn, H., Corrosive Response of the Interface Tissue to Dental Implants, Implant Prosthodontics Surgical and Prosthetic Techniques for Dental Implants, M. J. Fagan, Jr. et al., Eds., Yearbook Medical Publishers, Littleton, MA, 1991, pp. 293-304. 

RIS in austenitic steels has been well studied. For example, in irradiated 304 stainless steel, the Cr that is added for corrosion resistance can be depleted at grain boundaries, while elements such as Ni and Si are enriched [32]. This can change the composition of grain boundaries and change their corrosion response. Fig. 7.9 shows a typical RIS profile for Cr, Ni, and minor elements at the grain boundary of a neutron-irradiated stainless steel [22,33]. At 290—310°C, the depletion of Cr and enrichment of... 

By choosing the proper correlation algorithm, it is possible to realise sensitive filters for other types of defects (e.g. corrosion). Fig. 5.2 shows an example for the suppression of signals which do not exhibit the expected defect stmcture (Two parallel white lines near upper central rim portion of Fig. 5.2). The largest improvement in SNR is obtained here by using the expression (ai ai+x /ai+yj), since for a gradiometric excitation, one expects the crack response to show two maxima (a, aj+x) with a minimum (a m) in the centre (see Fig. 5.3). 

The operation is quite simple One sets the frequency to the lowest value, adjusts the gain and phase to the desired sensitivity using a special calibration standard discussed below and performs a zero-compensation on a defect free zone of the standard. Now one is ready to test. As one slides the probe across the surface of an aluminum structure, a signal response will be indicative of the presence of corrosion or of the presence of a subsurface edge. 

Corrosion associated with the action of micro-organisms present in the corrosion system. The biological action of organisms which is responsible for the enliancement of corrosion can be, for instance, to produce aggressive metabolites to render the environment corrosive, or they may be able to participate directly in the electrochemical reactions. In many cases microbial corrosion is closely associated with biofouling, which is caused by the activity of organisms that produce deposits on the metal surface. 

Another ak pollutant that can have very serious effects is hydrogen sulfide, which is largely responsible for the tarnishing of silver, but also has played a destmctive role in the discoloration of the natural patinas on ancient bronzes through the formation of copper sulfide. Moreover, a special vulnerabihty is created when two metals are in contact. The electromotive force can result in an accelerated corrosion, eg, in bronzes having kon mounting pins. 

Under the Comprehensive Environmental Response, Compensation, and LiabiHty Act (CERCLA)/RCRA regulations in effect at the end of 1986 bromine is regulated as a hazardous waste or material. Therefore, it must be disposed of in an approved hazardous waste faciHty in compliance with EPA and/or other appHcable local, state, and federal regulations and should be handled in a manner acceptable to good waste management practice. The reportable quantity is 45.4 kg for corrosivity (62). 

Alloys having varying degrees of corrosion resistance have been developed in response to various environmental needs. At the lower end of the alloying scale are the low alloy steels. These are kon-base alloys containing from 0.5—3.0 wt % Ni, Cr, Mo, or Cu and controlled amounts of P, N, and S. The exact composition varies with the manufacturer. The corrosion resistance of the alloy is based on the protective nature of the surface film, which in turn is based on the physical and chemical properties of the oxide film. As a rule, this alloying reduces the rate of corrosion by 50% over the fkst few years of atmosphere exposure. Low alloy steels have been used outdoors with protection. 

Surface preparation of the dental implant prior to implantation wiH have an effect on corrosion behavior, initial metal ion release, and interface tissue response (316). The titanium and titanium aHoy dental implants in present use have many forms to assist bone ingrowth attachment including cylinders with holes, screw threaded surfaces, porous surfaces, and other types of roughened surfaces. Methods used to produce porous surfaces iaclude arc plasma... 

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