Ferrous and Non Ferrous metals.pptx

Ferrous and non ferrous materials

1. Ferrous and Non Ferrous metals Limitations of plain carbon steels Cannot be strengthened above 690 MN/m2 without loss of ductility and impact resistance. The depth of hardening is limited. Must be quenched very rapidly to obtain a fully martenstic structure, leading to the possibility of quench distortion and cracking. Have poor impact resistance at low temperatures. Alloy steels containing a number of alloying elements have been developed to overcome these deficiencies.

2. ALLOY STEELS A homogeneous mixture or solid solution of two or more metals, the atoms of one replacing or occupying interstitial positions between the atoms of the other. The principal alloying elements used are : Manganese ( Mn ), nickel (Ni), chromium (Cr), molybdenum(Mo), tungsten (W), vanadium (V), cobalt (Co), silicon (Si), boron (B), copper (Cu), titanium (Ti) and niobium ( Nb ). Low Alloy steel (Alloying elements<=8%) High Alloy steel (Alloying elements>8%)

3. Effect of alloying elements Carbon Carbon is the primary hardening element in steel.  Hardness and tensile strength increases as carbon content increases.  Ductility and weld-ability decreases with increasing carbon. Manganese   Beneficial to surface quality especially in resulfurized steels. Manganese contributes to strength and hardness, but less than carbon.  The increase in strength is dependent upon the carbon content.  Increasing the manganese content decreases ductility and weldability , but less than carbon.

4. Phosphorus   Increases strength and hardness and decreases ductility and notch impact toughness of steel.  Higher phosphorus is specified in low-carbon free-machining steels to improve machinability . Sulphur Decreases ductility and notch impact toughness especially in the transverse direction.  Weldability decreases with increasing sulphur content.  Sulphur is found primarily in the form of sulfide inclusions.  The only exception is free-machining steels, where sulphur is added to improve machinability .

5. Silicon   Is one of the principal deoxidizers used in steelmaking.  Silicon is less effective than manganese in increasing as-rolled strength and hardness. Increases magnetic properties Copper Is beneficial to atmospheric corrosion resistance when present in amounts exceeding 0.20. Copper (0.10% to 0.50%) in significant amounts is detrimental to hot-working steels. Copper negatively affects forge welding, but does not seriously affect arc or oxyacetylene welding. Copper can be detrimental to surface quality. 

6. Lead   Is virtually insoluble in liquid or solid steel. Lead is sometimes added to carbon and alloy steels by means of mechanical dispersion during pouring to improve the machinability . Boron   Is added to improve hardenability . Boron-treated steels are produced to a range of 0.0005 to 0.003%. Improves machinablity and cold forming capacity Chromium   Is commonly added to steel to increase corrosion resistance and oxidation resistance Also increases the hardenability , and improves high-temperature strength. 

7. Nickel Is a ferrite strengthener.  Nickel does not form carbides in steel.  It remains in solution in ferrite, strengthening and toughening the ferrite phase.  Nickel increases the hardenability and impact strength of steels.  Molybdenum   Increases the hardenability of steel.  Molybdenum may produce secondary hardening during the tempering of quenched steels. It enhances the creep strength of low-alloy steels at elevated temperatures Aluminum   Is widely used as a deoxidizer.  Aluminum can control austenite grain growth in reheated steels and is therefore added to control grain size. Aluminum is the most effective alloy in controlling grain growth prior to quenching.

8. Titanium, zirconium, and vanadium Are also valuable grain growth inhibitors, but there carbides are difficult to dissolve into solution in austenite. Vanadium increases the yield strength and the tensile strength of carbon steel.

9. High strength low alloy steels (HSLA) Not hardened by heat treatments Yield strength (289-482) Mpa , tensile strength (414 – 621) Mpa . Microstructure will be in the form of ferrite- pearlite Low carbon content (less than 0.2 %) , 1.0 % Mn and less than 0.5% of other alloying elements Provides increased strength to weight ratio. Especially preferable for thinner sections. Superior in weldablity , formablity , toughness & strength compared to plain carbon steels. They can be annealed, normalized, or stress relieved. Applications Trucks, construction equipment, off-highway vehicles, mining equipment and other heavy-duty vehicles use HSLA sheets or plates for chassis components, buckets, all type Structural works. Applications such as offshore oil and gas rigs, single-pole power- Transmission towers, railroad cars, and ship construction.

10. High alloy steels Stainless steel  In metallurgy stainless is defined as an iron-carbon alloy with a minimum of 11.5 wt% chromium content. Stainless steels are High alloy steels and have superior corrosion resistance because they contain relatively large amount of chromium Selecting a Stainless Steel Corrosion resistance Magnetic properties Resistance to oxidation and sulfidation Ambient strength Ductility Resistance to abrasion and erosion Toughness Elevated temperature strength Cryogenic strength Thermal conductivity Electrical resistivity etc

11. Types of Stainless steel Austenitic grades Ferrite grades Martensitic Precipitation-hardening martensitic stainless steels Duplex stainless steels Austenitic grades –Features Compostion:0.15% carbon;16% -26%Chromium ,nickel-8-24 % Magnese-15% Retain austenitic structure Austenitic steels have Face Centered Cubic structure. Non magnetic in the annealed condition and can be hardened only by cold working. Possess excellent cryogenic properties and high temperature strength.

12. Ferritic grades Highly corrosion-resistant, but less durable than austenitic grades. Compostion -less than 0.2%carbon and 16 – 20 % chromium and very little nickel, molybdenum; some, aluminum or titanium. Common ferritic grades include 18Cr-2Mo, 26Cr-1Mo, 29Cr-4Mo, and 29Cr-4Mo-2Ni. Ferritic grades are chromium containing alloys with bcc crystal structure The ferritic alloys are Ferro magnetic They can have good ductility and formablity , but high temperature strength are relatively poor compared to austenitic grades

13. Martensitic grades Compostion:1.2% carbon;12% -18 %Chromium Martensitic stainless steels are not as corrosion-resistant as the other two classes Extremely strong and tough, as well as highly machinable . Heat treatable. Body centered cubic crystal structure in the hardened condition. Resistant to corrosion only in the mild environment Excess carbides present to increase wear resistance or to maintain cutting edges Precipitation –hardening martenstic stainless steels Precipitation hardening stainless steels are chromium-nickel alloys. PH most common grade;17%chromium 4%nickel. Precipitation hardened to get higher strengths than the other martensitic grades Precipitation-hardening stainless steels may be either austenitic or martensitic in the annealed condition.

14. Duplex stainless steels Duplex stainless steels are a mixture of BCC ferrite and FCC austenite crystal structures. The percentage in each phase is a dependent on the composition and heat treatment(mostly 40 – 60 %). Most Duplex stainless steels are intended to contain around equal amounts of ferrite and austenite phases in the annealed condition. The primary alloying elements are chromium and nickel.  Duplex stainless steels generally have similar corrosion resistance to austenitic alloys. Duplex stainless steels also generally have greater tensile and yield strengths, but poorer toughness than austenitic stainless steels. Stainless steel grades 200 Series — austenitic chromium-nickel-manganese alloys 300 Series — austenitic chromium-nickel alloys 400 Series — ferritic and martensitic chromium alloys 500 Series — heat-resisting chromium alloys 600 Series — martensitic precipitation hardening alloys

15. Tool steels Tool steel refers to a variety of carbon and alloy steels that are particularly well-suited to be made into tools . Tool steels contain more alloying elements than normal alloy steels. Hardness, resistance to abrasion, ability to hold a cutting edge, and/or their resistance to deformation at elevated temperatures are the major features.

16. Types of tool steels

17. Defining property AISI grade Significant characteristics Water-hardening W Cold-working O Oil-hardening A Air-hardening; medium alloy D High carbon; high chromium Shock resisting S Tungsten base High speed T Tungsten base M Molybdenum base Hot-working H H1-H19: chromium base H20-H39: tungsten base H40-H59: molybdenum base Plastic mold P Special purpose L Low alloy F Carbon tungsten

18. Water-hardening grades W-grade tool steel is water quenched tool . W-grade steel is essentially high carbon This type of tool steel is the most commonly used tool steel because of its low cost compared to other tool steels. They work well for small parts and applications where high temperatures are not encountered; above 150 °C (300 °F) it begins to soften to a noticeable degree. Hardenability is low so W-grade tool steels must be quenched in water. These steels are rather brittle. Typical applications for various carbon compositions are: 0.60—0.75% carbon: machine parts, chisels, setscrews 0.76—0.90% carbon: forging dies, hammers, and sledges. 0.91—1.10% carbon: drills, cutters, and shear blades. 1.11—1.30% carbon: small drills, lathe tools, razor blades

19. Cold-working grades Grade-O refers to oil hardening and grade-A refers to air hardening. The toughness of O-grade and A-grade tool steels are increased by alloying with silicon, Manganese, Silicon, Chromium. These tool steels are used on larger parts More alloying elements are used in these steels, as compared to water-hardening grades. These alloys increase the steels' hardenability , and thus require a less severe quenching process. These steels are also less likely to crack. D-grade tool steels contain between 10% and 18% chromium and carbon from 1.50- 2.35 %. These steels retain their hardness up to a temperature of 425 °C (800 °F). Common applications for these grade of tool steel is forging dies, die-casting die blocks, and drawing dies.

20. Shock resisting grades S-grade tool steel are designed to resist shock at both low and high temperatures. A low carbon content is required for the necessary toughness (approximately 0.5% carbon). High speed grades T-grade and M-grade tool steels are used for cutting tools where strength and hardness must be retained at temperatures up to or exceeding 760 °C (1400 °F). M-grade tool steels were developed to reduce the amount of tungsten and chromium required. T (also known as 18-4-1) is a common T-grade alloy. Its composition is 0.7% carbon, 18% tungsten, 4% chromium, and 1% vanadium.

21. Hot-working grades H-grade tool steels were developed for strength and hardness during prolonged exposure to elevated temperatures. All of these tool steels use a substantial amount of carbide forming alloys. H1 to H19 are based on a chromium content of 5%; H20 to H39 are based on a tungsten content of 9 to 18% and a chromium content of 3 to 4%; H40 to H59 are molybdenum based. Special purpose grades P-grade tool steel is short for plastic mold steels. They are designed to meet the requirements of zinc die casting and plastic injection molding dies. L-grade tool steel is short for low alloy special purpose tool steel. L6 is extremely tough. F-grade tool steel is water hardened by substantially more wear resistant than W-grade tool steel.

22. Maraging Steels Maraging steel is essentially free of carbon, which distinguishes it from most other types of steel. The result is a steel which Possesses high strength and toughness. A special class of low carbon ultra-high strength steels which derive their strength not from carbon but from precipitation of inter-metallic compounds. Maraging steels are carbon free iron-nickel alloys with additions of cobalt, molybdenum, titanium and aluminium.  Cobalt is added in percentages up to 12% to accelerate the precipitation reactions. The term maraging is derived from the strengthening mechanism, which is transforming the alloy to martensite with subsequent age hardening . Applications Aerospace, e.g. undercarriage parts and wing fitting, Tooling & machinery, e.g. extrusion press rams and mandrels in tube production, gears and fasteners. They are suited to engine component applications such as crankshafts,

23. Non ferrous alloys The more common non-ferrous materials are the following metallic elements and their alloys: Copper Aluminium Magnesium Lead Nickel Tin Zinc Cobalt etc.

24. COPPER The main grades of raw copper used for cast copper base alloys are High conductivity copper (electrolytic) having min 99.9% Cu. The oxygen content may be of the order 0.40%, Pb and Fe less than 0.005% Ag 0002% and Bi less than 0.001%. Electrolytic copper is used for electrical purposes. Deoxidized copper having min 99.85% Cu, less than 0.05%As, 003% Fe and 0.003% Bi. Other elements may be of the 0.05% P 0.01% Pb , 0.10% Ni, 0.003% and 0.005% Ag and Sb respectively. Arsenical deoxidized copper having 0.4% As, 0.04% P and remaining copper. It is used for welded vessels and tanks. Arsenical touch pitch copper containing 0.4% As, 0.065% oxygen,0.002% Pb , 0.15% Ni 0.006% Ag, 0.01% Sb and less than 0.005% BI, less than 0.020% Fe and remaining copper. Oxygen free copper contains 0.005% Pb , 0.001% Ni, 0.001% Ag and less than 0.0005% and 0.001 % Fe and Bi respectively. It is melted and cast in non- oxidising atmosphere

25. Properties and applications of Copper : Properties Excellent resistance to corrosion. Non-magnetic properties. Easy to work, it is ductile and malleable. Moderate to high hardness and strength. High thermal and electrical conductivity. . It can be easily polished, plated and possesses a pleasing appearance. Resistance to fatigue, abrasion and corrosion. It can be soldered, brazed or welded. Very good machinability . . Ease of forming alloys with other elements like Zn, Sn , AI, Pb , Si, Ni, etc. Applications ( i ) Electrical parts, (ii) Heat exchangers, (iii) Screw machine products, (iv) For making various copper alloys, such as brass and bronze,

26. Copper Alloys High strength and corrosion resistance, a combination desirable for marine applications. Possess excellent corrosion resistance, electrical and thermal conductivities and formability. High wearing properties, hardness. Some copper alloys are selected for decorative applications because of appearance. Elements such as aluminium, zinc, tin, beryllium, nickel, silicon, lead etc., form alloys with copper. Classification of Copper alloys : High copper alloys - contains 96.0 to 99.3% copper. Possess enhanced mechanical properties due to the addition of small amounts of alloying elements such as chromium, zirconium, beryllium and cadmium. A few typical high copper alloys are: ( i ) Cu,1% Cd (ii) Cu, 0.8% Cr  (iii) Cu, 0.12-0.30% Zr (iv) Cu, 1.5-2.0% Be Used for electrical and electronic components resistance welding electrodes, wire conductors, diaphragms .

27. BRASSES Brasses contain zinc as the principle alloying element. Brasses are subdivided into three groups; ( i ) Cu-Zn alloys,  (ii) Cu- Pb -Zn alloys or leaded brasses, and (iii) Cu-Zn- Sn alloys or tin brasses. Zinc in the brass increases ductility along with strength. Brass has high resistance to corrosion and is easily machinable also acts as good bearing material. Brass possesses greater strength than copper, however, it has lower thermal and electrical conductivity.  Various types of brasses are discussed below: (1) Gilding metal Range from 5% to 15% Zn( balance Cu) and possess shades of colour from the red of copper to a brassy yellow. They are supplied mainly in the form of sheet strip and wire for jewellery and many other decorative purposes. Like copper, gilding metal is hardened and strengthened by cold work. Gilding metal is used making coins, medals, tokens, fuse caps etc.

28. (2) Cartridge brass - contains 70% Cu and 30% Zn. In the fully annealed condition it has a tensile strength of over 300 N/mm2. Greater % elongation and tensile strength cold deformation in presses and by spinning or other means, Used for cupped articles like the caps of electric lamp bulbs, door furniture etc. Cartridge brass work hardens when deformed in the cold, and must be annealed if many successive operations are to be performed. (3) Admiralty brass Admiralty brass contains Cu 71%, Zn 28%, and Sn 1%. The small amount of tin added to brass improves its resistance to certain types of corrosion. Used exacting conditions of marine condensers. widely used for the tubes and other parts of condensers cooled by fresh water and for many other purposes. For such applications, the modern alloy contains about 0.04%. Arsenic, which improves resistance to a penetrative form of corrosion known as dezincification.

29. (4) Aluminium brass - contains 76% Cu, 22% Zn and 2% Al ,a little arsenic is added to inhibit dezincification. In contact with sea water, a protective film builds up on the surface of this alloy in the early stages of corrosion and prevents further attack. Moreover, if the film is damaged, by the abrasive action of sand particles, for instance, it is self-healing. (5) Basis brass - contains copper 61.5-64%, the remainder being zinc. Basis brass is used for press work where a relatively cheap material is required, The main commercial forms are sheet, strip and wire.   (6) Muntz metal or yellow metal - contains 60% of copper and 40% of Zn Essentially a hot working material. It is manufactured in the form of hot rolled plate, and hot rolled rod or extruded sections in a great variety of shapes and sizes. Yellow metal is frequently used as a brazing alloy for steel. Other applications of muntz metal are as: Ship sheathing ,Perforated metal ,Valve stems ,Condenser tubes ,Architectural work etc.

30. (7) Leaded 60 : 40 brass - is the chief material fed to automatic lathe and similar machines, usually in the form of extruded bar . Lead is added to Cu-Zn alloy to promote machinability , The lead content ranges from about 0:5% to as much as 3.5%. 60:40 brass, tends to improve the weldability , ductility and impact strength. used for: Keys , Lock-parts, Gears, Clock parts, Valve parts ,Pipe unions. (8) Nava1 brass - contains Cu 60%, Zn 39.25% and Sn 0.75%. The purpose of tin is to Improve the resistance to corrosion. Used for structural applications and for forgings, especially in cases where contact with sea water Naval brass is obtainable as hot-rolled plate particularly for marine condenser plates, and in the form of extruded rod for the production of machined or hot forged components. Other applications of naval brass are: Propeller shafts ,Valve stems ,Pump impellers etc. (9) Admiralty brass - contains 71 % Cu, 28% Zn, and 1% Sn . It is used for decorative and architectural applications, screw machine products, heat exchanger components, pump impellers

31. BRONZE Bronze is basically an alloy of copper, tin and elements other than nickel or zinc . Bronze possesses superior mechanical properties and corrosion resistance than brass. Bronze is comparatively hard and it resists surface wear. Bronze can be shaped or rolled into wire, rod and sheets. Types of bronzes ( i ) Phosphor Bronze - deoxidized with phosphorus during the refining process and hence are known as phosphor bronze. The amount of phosphorus may range from a trace to about 0.35% or even higher in some special grades. In amounts greater than 1.0% phosphorus causes excessive brittleness A phosphor bronze containing approximately 4% each of tin, lead and zinc has excellent free-cutting characteristics. Standard Phosphor bronze for bearing applications contains 90% Cu, 10% Sn (min), and 0.5% P (min). It has a tensile strength of 220-280 N/mm2 Phosphor bronze for gears contains 88% Cu, 12% Sn , 0.3% (max) Zn, 0.50% (max) Pb and 0.15% (min) P. It has a tensile strength of 220-310 N/mm2. This alloy is also utilised for general bearings, where its rigidity is of advantage.

32. Leaded phosphor bronze contains 87% Cu, 7.5% Sn , 2.0% (max) Zn, 3.5% Pb , 0.3% (min) P and 1.0% (max) Ni. It has a tensile strength of 250 N/mm2 This material is satisfactory for many bearing applications. Properties of phosphor bronze (a) has high strength and toughness (b) is resistant to corrosion (c) has good load bearing capacity, and (d) has low coefficient of friction. Applications (a) bearing applications (b) making pump parts, linings, springs, diaphragms, gears, clutch discs, bellows etc. (ii) Aluminium bronzes – contains Cu -89-91,% Al, 6-8% ,Fe 1.5 -3.5% , Sn 0.35 % Mn 1%(max) Properties of Aluminium bronzes : Good strength ,High corrosion resistance ,Good heat resistance ,Good cold working properties, etc, Used in -Bearings, Valve seats ,Gears ,Propellers ,Slide valves, Cams ,Imitation jewellery , Pump parts etc. (iii) Silicon bronzes – contains Si 1-4%, Fe 0.5-1.0% , Mn 0.25-1.25% ,and balance Cu Lead when added as 0.5% improves machinability . Used in : Bearings ,Roll mill sleepers, Screwdown nuts ,Boiler parts ,Die cast parts etc. (

33. GUN METAL   Gun metal is an alloy of copper, tin and zinc. Zinc cleans the metal and increases its fluidity. A small amount of lead may be added to improve cast ability and machinability . Types Admirality gun metal contains 10% Sn , 2% Zn, 1.5% max Ni and balance Cu. It has tensile strength of 260-340 N/mm2. It is used for pumps, valves and miscellaneous castings. Leaded gun metal contains 7% Sn , 2.25% Zn, 0.3% Pb , 5.5 and balance copper. It has a tensile strength of 430-480 N/rr.m2. Nickel gun metal contains 5% Sn , 5% Zn, 5% Pb , 2.0% max Ni. It has a tensile strength of 200-270 N/mm2. This is among the most widely used grades, particularly where high pressure is required. In general gun metal is used for Bearings ,Steam pipe fittings ,Hydraulic valves and gears, etc

34. Cupronickel or copper-nickel Is an alloy of copper that contains nickel and strengthening elements, such as iron and manganese. Cupronickel is highly resistant to corrosion in seawater. It is used for piping, heat exchangers and condensers in seawater systems as well as marine hardware, and sometimes for the propellers, crankshafts etc. A more familiar common use is in silver- coloured modern circulation coins . A typical mix is 75% copper, 25% nickel, and a trace amount of manganese. It is used in thermocouples, and the 55% copper/45% nickel alloy constantan is used to make resistors, thermocouples, and rheostats Monel metal is a nickel-copper alloy, containing minimum 63% nickel and 31.5 percent copper, with small amounts of iron, manganese, carbon, and silicon. Stronger than pure nickel, Monel alloys are resistant to corrosion by many agents, including rapidly flowing seawater. They can be fabricated readily by hot- and cold-working, machining, and welding.

35. BEARING MATERIALS Bearings support moving parts, such as shafts and spindles, of a machine or mechanism. Bearings may be classified as RoIling contact (i.e., Ball and roller) bearings. Plain bearings. Copper-based alloys Bronze covers a large number of copper alloys with varying percentages of Sn , Zn and Pb . Bronze is one of the oldest known bearing materials.   Typical compositions of bearing bronze arc: Cu-80% , Sn -10% , Pb -10%   Cu-85% , Sn -15% Bronze (10 to 14% tin remainder copper) is used in the machine and engine industry for bearing bushes made from thin walled drawn tubes. Copper-based alloys are employed for making bearings required to resist heavier pressures such as in railways.

36. Babbitt metal Babbitt metal is most commonly used as a thin surface layer in a complex, multi-metal structure Babbitt metal is characterized by its resistance to galling. Babbitt metal is soft and easily damaged Its structure is made up of small hard crystals dispersed in a softer metal, which makes it a metal matrix composite. As the bearing wears, the softer metal erodes creating paths for lubricant between the hard high spots that provide the actual bearing surface . When tin is used as the softer metal, friction causes the tin to melt and function as a lubricant, protecting the bearing from wear when other lubricants are absent.

37. ALUMINIUM AND ITS ALLOYS Aluminium is a silvery white metal and it has the following characteristics: ( i ) It is a light metal, with a density about a third that of steel or brass. (ii) Aluminium is a very good conductor of electricity. (iii) Aluminium has a higher resistance to corrosion than other metals, but film of oxide may forms on its surface. (iv) Aluminium is a good conductor of heat. (v) Aluminium is very ductile. . (vi) Aluminium is non-magnetic. (vii) Melting point of pure aluminium is about 650 C Although pure aluminium is not particularly strong, it forms strength alloys with other metals such as CU, Cr, Ni, Fe, Zn, Mn , Si and Mg. ( i ) Some of these aluminium alloys are more than 4 times strong as the same weight of mild steel. (ii) They are malleable and ductile. (iii)They exhibit toughness and become stronger at temperaturebelow the ordinary atmospheric range. (iv)They do not work well at temperatures of the order of 300-4OO O C. (v) Aluminium and its alloys can be (a) Cast (b) Forged (c) Welded (d) Extruded (e) Rolled, etc.

38. Uses of AI and Al-alloys ( i ) Transportation industry-structural frame-work, engine parts, trim and decorative features, hardware, doors, window frames, tanks, furnishing and fittings,trains , trucks, buses, automobile cars and aeroplanes use many component parts made up of aluminium alloys. (ii) Overhead conductors and heat exchanger parts. (iii) In food industry, aluminium alloys find applications as food preparation equipments(pans, etc.), refrigeration, storage containers, bakery equipment, shipping containers, etc. (iv) In architectural field, aluminium alloys find uses such as window farmes , doors hardware, roofing, coping sills, railings, fasteners, lighting fixture solar shading, grills, etc. (v) Cryogenic applications. (vi) As heavy duty structures such as travelling cranes, hoists, conveyor supports, bridges, etc. (vii) In process industries, parts made up of aluminium and its alloys are used to handle organic chemicals, petrochemicals and drugs. Tanks, pipes, heat exchangers, gratings, smoke-stacks, precipitators, centrifugal valves, fittings, etc. are produced from aluminium alloys.

39. Types of aluminium alloys Aluminium alloys Al- Mn Al-Mg Al-Mg- Mn Al-Mg-Si Al-CU-Mg Al-Cu-Si Al-CU-Mg- Pb Al-Mg-Si- Pb Al-Zn-Mg-Cu Aluminium alloys can be classified as follows: (a) Wrought alloys (b) Cast alloys (c) Heat-treatable alloys (d) Non-heat-treatable alloys.

40. CERAMICS Ceramics are inorganic non metallic materials which are formed by the action of heat. The most important of these were the traditional clays , made into pottery , bricks , tiles and the like, along with cements and glass . Mechanical properties Ceramic materials are usually ionic or covalent bonded materials, and can be crystalline or amorphous . Has less tensile strength High hardness due to brittility High compressive strength Poor toughness wear-resistant thermal insulators electrical insulators nonmagnetic oxidation resistant prone to thermal shock and chemically stable.

41. Classification of ceramics Ceramics can also be classified into Oxides : Alumina , zirconia . Non-oxides : Carbides , borides , nitrides , silicides . Carbides It is a compound of carbon with a less electronegative element. For example Fe 3 C ( cementite ), is formed in steels to improve their properties.   Examples Calcium carbide , Silicon carbide ( SiC ), Tungsten carbide , Cementite , Boron carbide , Tantalum carbide , Titanium carbide , Silicon carbide Silicon carbide ( Si C ) ( carbarundum ) It is a compound of silicon and carbon bonded together to form ceramics .

42. Properties of carbides High strength Low thermal expansion High thermal conductivity High hardness High elastic modulus Excellent thermal shock resistance Superior chemical inertness

43. Applications of SiC Fixed and moving turbine components Suction box covers Seals, bearings Ball valve parts Hot gas flow liners Heat exchangers Semiconductor process equipment Abrasives Disc brake Diesel particulate filter Cutting tools Coarse to fine grit sandpapers

44. Aluminum Oxide, (Al2O3) Alumina Aluminium oxide is of aluminium with the chemical formula Al 2 O 3. Being very hard, it is used as an abrasive. Having a high melting point, it is used as a refractory material.   Key Properties Hard, wear-resistant Excellent dielectric properties Resists strong acid and alkali attack at elevated temperatures Good thermal conductivity Excellent size and shape capability High strength and stiffness Aluminium oxide is an electrical insulator But has a relatively high thermal conductivity (40 W/m K). In its most commonly occurring crystalline form, called corundum or α-aluminium oxide As a component in cutting tools . [3]

45. Applications Gas laser tubes Wear pads Seal rings High temperature electrical insulators High voltage insulators Furnace liner tubes Thread and wire guides Electronic substrates Abrasion resistant tube and elbow liners Laboratory instrument tubes and sample holders Instrumentation parts for thermal property test machines Grinding media Over 90% of which is used in the manufacture of aluminium metal. Health and medical applications include it as a material in hip replacements , It is widely used as a coarse or fine abrasive , including as a much less expensive substitute for industrial diamond . Many types of sandpaper use aluminium oxide crystals. Aluminium oxide is widely used in the fabrication of superconducting devices,

46. Partially stabilized Zirconia ( PSZ) (ZrO 2 ) Tensile strength higher than alumina Toughness and fracture toughness is better than other ceramics High elavated temperature strength Applications of ZrO 2 Precision ball valve balls and seats High density ball and pebble mill grinding media Rollers and guides for metal tube forming Thread and wire guides Hot metal extrusion dies Deep well down-hole valves and seats Powder compacting dies Marine pump seals and shaft guides Oxygen sensors High temperature induction furnace susceptors Fuel cell membranes Electric furnace heaters over 2000°C in oxidizing atmospheres

47. NITRIDES Nitride is a compound of nitrogen with a less electronegative element. Silicon nitride (Si 3 N 4 ) is a hard, solid substance, that can be obtained by direct reaction between silicon and nitrogen . For machining of steel , it is usually coated by titanium nitride . Cubic boron nitride is used in grinding wheel in the form of abrasive. APPLICATIONS The largest market for silicon nitride components is in reciprocating (diesel and spark ignited) engines for combustion components and wear parts. glow plugs for faster start-up Precombustion chambers turbocharger exhaust gas control valve for increased acceleration. fixtures in induction heating and resistance welding exploit the electrical insulation, wear resistance, low thermal conductivity and thermal shock resistance of the material. Nozzles, thermocouple sheats and melting crucibles for handling molten aluminium, zinc, tin and lead alloys. Arc welding nozzles for high strength, electrical resistance and thermal shock resistance of the material.

48. Sialon It is a silicon nitride ceramic with a small percentage of aluminum oxide added. It is highly thermal shock resistant, strong, and is not wet or corroded by aluminum, brass, bronze, and other common industrial metals.   Properties Excellent thermal shock resistance Not wetted or corroded by nonferrous metals High strength Good fracture toughness Good high temperature strength Low thermal expansion Good oxidation resistance  Retain tensile strength upto 1400 O C Application Thermocouple protection tubes for nonferrous metal melting Machining nickel based alloys Immersion heater and burner tubes Degassing and injector tubes in nonferrous metals Metal feed tubes in aluminum die casting Welding and brazing fixtures and pins

49. COMPOSITE MATERIALS Composite is a mixture of two or more distinct constituent or phases Both constituents have to be present in reasonable property ,say 5%. The constituent that is continuous and is often but not always ,present in the greater quantity in the composite is termed as matrix. The second constituent is referred to as the reinforcing phase or reinforcement as it reinforces the mechanical properties of matrix. The reinforcement is harder, stronger and stiffer than matrix in most causes. Functions of Matrix Material: It takes the load and transfers it to the reinforcement. It binds or holds the reinforcement and protects the same from mechanical or chemical damage that might occur by abrasion of their surface (in particular with fibers). It also separates the individual fibers and prevents brittle cracks from passing completely across the section of the composite. Functions of Reinforcing Material: The major load on the composite is carried by the reinforcing phase.

50. Advantages of composite materials High strength to weight ratio High stiffness Low density High young’s modulus & tensile strength Increase in the toughness Types of composites Metal Matrix composites Ceramic Matrix composites Polymer Matrix composites Metal Matrix composites(MMC) Matrix - Aluminium, Copper, Nickel based alloys, Iron etc Reinforcement – Carbon, Silicon Carbide( SiC ),Aluminium oxide(Al 2 O 3 ), Tungsten carbide etc.

51. Applications of Al/ SiC MMC: Automotive -Reciprocating and static engine components, braking systems Aerospace -Struts, undercarriage, guided weapons, satellites Rail Engineering -Engine and braking components Military - Gun barrel overwraps, missiles ( aerofoils and fins, bodies and blast pipes),military , diesel components. Electronic - Substrates and packaging, thermal management, racking, power sources and storage Marine - Propellers, impellers, pressurized hulls, marine diesel components Industrial - Reciprocating and high speed machinery, precision equipment Sport/Leisure - Rackets, cycles and frames, motor racing, golf clubs

52. Ceramic Matrix composites(CMC): In case of CMC ceramic materials are used as matrix. Some of the ceramic materials used are Silicon carbide Alumina Glass ceramics Carbon Advantages: Co efficient of thermal expansion of ceramics is low Thermal and electrical conductivity is less than MMC CMC can withstand high temperature and can provide high strength than MMC Disadvantages: CMC can withstand very high temperature only if the reinforcement is a high temperature withstanding material After processing the thermal stress in MMC can be relieved from plastic deformation , whereas it is not possible in CMC

53. Types of CMCs: Alumina matrix composites SiC whisker reinforced CMC-Used for cutting tools and manufacturing industries Zirconia toughened alumina Glass ceramic matrix composites Carbon-carbon composites Applications of CMCs: Applications: Aerospace -After burners, brakes, heat shields, nozzles Automobile - Brakes Manufacturing- Thermal insulation, cutting tools, wire drawing dies Medical - Fixation plates

54. POLYMER MATRIX COMPOSITES: Types of polymers: Thermosets Thermo plastics-Crystalline and Non-crystalline Rubber Advantages: Low strength Low strength than MMC & CMC Low fracture toughness Disadvantage: Low working temperature Low coefficient of thermal expansion Dimensional instability Commercial PMCs: Fibre reinforced epoxies Carbon-fiber reinforced plastic or CFRP Glass-fiber reinforced plastic or GFRP (also GRP). Aramid fibre reinforced plastic

55. Applications: Industrial - Solar collectors, Electrostatic precipitation plates, Fan blades, Water tanks Recreational - Television antennas, Snow mobiles Construction - Seating, bath tabs, roof sections, bus shelters Aerospace - Wing ribs, helicopter blades, landing gears, cockpit hatch covers, escape doors Automobile - Crash members, leaf springs, car bodies Electrical - Panels, housings, switch gear Chemical - Pipes, tanks, pressure vessels, hoppers, valves, pumps