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FUEL VARIABLES AND CORROSION RESISTANT MATERIALS FOR AUTOMOTIVE EXHAUST THERMAL REACTORS

THE EFFECT OF SEVERAL FUEL VARIABLES ON OXIDATIVE CORROSION OF METALS IN AUTOMOTIVE EXHAUST GAS AFTER-BURNERS HAS BEEN DETERMINED FOR THE NORMAL THERMAL REACTOR OPERATING RANGE OF 1700 TO 1800 F. AT 1750 TO 1800 F., WHEN USED IN CONJUNCTION WITH TETRAETHYL LEAD ANTIKNOCK ADDITIVES, PHOSPHORUS TENDS TO SIGNIFICANTLY INCREASE CORROSION OF AFTERBURNER METALS. TEL ALONG WITH REQUIRED HALOGEN SCAVENGERS ALSO SIGNIFICANTLY INCREASES CORROSION. IT IS OF NO CONSEQUENCE WHETHER THE SCAVENGER IS ALL ETHYLENE DIBROMIDE (AVIATION MIX) OR A MIXTURE OF ETHYLENE DIBROMIDE AND ETHYLENE DICHLORIDE (MOTOR MIX). SULFUR WITHIN EASONALBLE CONCENTRATION LIMITS HAS LITTLE EFFECT ON HIGH TEMPERATURE OXIDATION IN A THERMAL REACTOR. TESTS WERE NOT MADE TO SHOW THE EFFECT OF PHOSPHORUS IN THE ABSENCE OF LEAD. HALOGEN TENDS TO MITIGATE THE CORROSION PROMOTING PROPERTIES OF LEAD. REDUCTION OF LEAD TO 0.5 GM/GAL WITH APPROPRIATE REDUCTIONS OF HALOGEN AND PHOSPHORUS GAVE CORROSION RATES PRACTICALLY IDENTICAL TO THOSE OBTAINED WHEN USING UNLEADED FUEL. THE LESS HIGHLY ALLOYED METALS SHOWED A DIRECT VARIATION IN OXIDATION RATE WITH AVERAGE MAXIMUM CYCLE TEMPERATURE. IN THE CASE OF THE MORE HIGHLY ALLOYED MATERIALS, THE OXIDATION RATE DID NOT APPEAR TO BE GREATLY AFFECTED BY AVERAGE MAXIMUM CYCLE TEMPERATURE UNTIL A CRITICAL TEMPERATURE WAS REACHED AT WHICH FURTHER INCREASES GREATLY INCREASED OXIDATION RATE. THE FERRITIC ALLOYS CONTAINING CHROMIUM AND ALUMINUM (OR-1 AND A-1821) PROBABLY HAVE ADEQUATE OXIDATION RESISTANCE TO MAKE THEM USEFUL FOR AFTERBURNER PARTS NOT SUBJECT TO TEMPERATURES EXCEEDING 1700 TO 1750 F. FOR THOSE COMPONENTS SUBJECT TO OCCASIONAL OVERTEMPERATURES, HIGHER ALLOY MATERIALS WILL BE REQUIRED BOTH FOR STRENGTH AND OXIDATION RESISTANCE. THE OXIDATION RESISTANCE OF THE LESS EXPENSIVE FERRITIC ALLOYS OR-1 AND A-1821 CAN BE CONSIDERABLY IMPROVED BY APPLICATION OF FLAME SPRAYED NICKEL--ALUMINUM OR NICKEL--CHROMIUM--ALUMINUM COATINGS. COATED MF-1 ALSO HAS EXCELLENT OXIDATION RESISTANCE IF THE COATING IS NOT DAMAGED. ELECTRON PROBE MICROGRAPHS OF THE OXIDATION SCALE INDICATE THAT METALS ACHIEVE OXIDATION RESISTANCE IN THERMAL REACTOR ENVIRONMENTS IN THE CLASSIC MANNER BY FORMATION OF A PROTECTIVE LAYER OF CHROMIUM OR ALUMINUM OXIDE ADJACENT TO THE METAL SURFACE. /AUTHOR/

  • Supplemental Notes:
    • Vol 10, No 9, PP 31-34, 9 FIG, 1 TAB, 3 REF
  • Authors:
    • Stoberg, J W
    • Rozmanith, A I
  • Publication Date: 1971-9

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  • Accession Number: 00217164
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 18 1971 12:00AM