Seminar on Material Science

SEMINAR ON MATERIAL SCIENCETOPIC:CORROSION

WHAT IS CORROSION ?corrosion is the gradual destruction of materials(usually metals) by chemical reaction with the environmentIn common words it means the oxidation of metals in presence of oxygenRust is a very common example of corrosioncorrosion reduces the strength of a material and makes it weak

RECIPE OF CORROSION

TYPES OF CORROSIONUNIFORM CORROSIONLOCALIZED/PITTING CORROSIONWIDE PITTING CORROSIONINTERGRANULAR CORROSIONINTRAGRANULAR CORROSIONGALVANIC CORROSIONSELECTIVE CORROSIONEXFLOITATION CORROSIONINTERFACIAL CORROSION

UNIFORM CORROSIONThis is also called general corrosionthis is produced due to an acid attack on the metalOn a polished surface this type of corrosion is seen when the surface becomes dullthis is the most common type of corrosion

LOCALISED/PITTING CORROSIONOn this type corrosion occurs in random pits pitting is most likely to occur in the presence of chloride ion combined with oxygen or oxidizing saltsthe rust bubbles indicate that pitting is occuring

INTERGRANULAR CORROSIONIntergranular corrosion is an attack on or adjacent to the grain boundaries of a metal or an alloy EXFOLIATION CORROSION:-it is a type of intergranular corrosion in which lifiting of suraface grains takes place

INTRAGRANULAR CORROSIONin this type of corrosion the boundaries of the crystallites of the material are more susceptible to corrosion than their insides

GALVANIC CORROSIONgalvanic corrosion is an electrochemical action of two or more dissimilar metals in the presence of an electrolyte and an electron conducting pathit is recoginizable at the point where two metals are joined the natural difference in metal potentials produce galvanic differences which produces corrosion

SELECTIVE CORROSION OR DEALLOYINGDealloying is a rare form of corrosion found in copper alloys,grey cast iron and someother alloys It occurs when the alloy looses the active metal components and retains the more corrosion resistant componentson the metal sufrace

INTERFACIAL CORROSIONCervic corrosion or contact corrosion produced at the region of contact with metals or metals with non metals example of this type of corrosionis seen in screws and bolts

PROTECTION FROM CORROSIONgalvanized surfaceplating,painting and application of enamel are the most common treatments to prevent corrosionthe coating provides protection from the surrounding corrosive environment

reactive coatingsif the environment is controlled ,corrosion inhibitors can often be added to itthese form an electrically insulated orchemically impermiable coating on exposed metal surfaces

ANODIZATIONalluminum alloys often undergo a surface treatment.metals surface is electrochemically coated in a baththis makes the metal more resistant to corrosion

BIOFILM COATINGSa new form of protectionhas been developed by appyling bacterialfilms to the surace of some metals in highly corrosive environmentthis process increases the corrosion resistant property of a metal

THE ENDpresentation by : ANMOL DATTSECTION:III BROLL NO: 26