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S18 Processos Mecânico-Metalúrgicos |
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Title:
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CORROSION RESISTANCE OF THE TITANIUM AS AUTOCLAVES MATERIAL
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Summary :
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USING THE POTENTIAL-PH SECTION OF THE HSC CHEMISTRY FOR WINDOWS 3.0 SOFTWARE (OUTOKUMPU OY, FINLAND) EH-PH DIAGRAMS OF THE NA-K-CL-S-TI-H2O SYSTEM AT 25, 100, 200 AND 300OC WERE CONSTRUCTED FOR SEVERAL ACTIVITIES OF THESE KEY ELEMENTS; COUPLES OF (EH, PH) VALUES CORRESPONDING TO EACH OF THE DOMAIN LIMITS BETWEEN THE PREDOMINANT SPECIES OF THE SYSTEM WERE TAKEN AND USED TO BUILD PTI-PH DIAGRAMS FOR THE SAME TEMPERATURES, WHERE
PTI = - LOG10 ATI . THE ANALYSIS OF THESE DIAGRAMS SHOWED THAT UNDER OXIDATIVE AQUEOUS SOLUTIONS AND CHEMICAL NEUTRALITY OR NOT EXTREMELY ACID OR ALKALINE CONDITIONS, THE TITANIUM METAL IS A GOOD AUTOCLAVE MATERIAL, BUT UNDER HIGHLY REDUCTIVE CONDITIONS IN EXTREMELY ACID CONDITIONS TITANIUM BECOMES UNSTABLE AND WILL BE CORRODED. ALSO, EVEN UNDER OXIDATIVE CONDITIONS, AN EXTREMELY ALKALINE AQUEOUS SOLUTION WILL CONDUCT TO THE FORMATION OF ALKALINE TITANATE SOLID WHICH SUBSEQUENTLY WILL DISSOLVE INTO DILUTE AQUEOUS SOLUTION AND CORRODE.
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Author :
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Andrade, Mônica Calixto de
Bastos, Ivan Napoleão
Ogasawara, Tsuneharu 0
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Paper View :
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