(a). Compaction of cast iron powder.(b) Sintering of Compacted Cast Iron

 

 

 

7.1 Objective:

The objective of this experiment is to get the green density of powders and their effect on the processing characteristics.

 7.2 Introduction:

Cast irons are basically iron-carbon alloys having carbon between 2.11% and 6.67%.   Eutectic reaction takes place during solidification. Alloys having Carbon between 2.11% and 4.3% are called hypo-eutectic cast irons. The alloy Containing 4.3% C is called eutectic cast iron, and the alloys containing between4.3% and 6.67% carbon are called hyper-eutectic cast irons. The cast ability is the best of a eutectic alloys. The industrial cast irons have carbon normally in the range of 2.11% to 4.0%, along with other elements like silicon, manganese, sulphur phosphorus in substantial amounts. Higher carbon content makes them more brittle. Cast irons are brittle, and cannot be forged, rolled, drawn etc. but can only be ‘cast’ into desired shape and size by pouring the molten alloy of desired composition into a mould of desired shape and allowing it to solidify. As casting is the only and exclusively suitable process to shape these alloys, so called cast irons. Its usefulness derives from its relatively low melting temperature. The alloy constituents affect its color when fractured.  White cast iron has carbide impurities which allow cracks to pass straight through. Grey cast iron has graphite flakes which deflect a passing crack and initiate countless new cracks as the material breaks.  Ductile cast iron has spherical graphite "nodules" which stop the crack from further progressing.

(a)   7.3 Compacted cast iron:

The formation of compacted iron depends on the chemical composition, section thickness and the process used for production.  Normally, 10-20% of the spheroidal graphite may be present, which requires C.E.V. of 4.00, and flake graphite should be avoided. In one of the production methods, nitrogen (—0.015%) is added to liquid alloy in ladle by adding nitride Ferro-manganese (80% Mn, 4% N, rest Fe). This method gives non-uniformity of structure and unsoundness in castings. In another method, an alloy (4-5% Mg, 8.5-10.5% Ti, 4-5.5% Ca, 1-1.5% Al, 0.2-0,5% Ce, 48-52% Si, rest Fe) in amounts 0.6-1.6% is added, as additions are made to produce S.G. iron. Sulphur content of iron should not be more than 0.035%. This method is section-sensitive as spheroids get formed in thin sections. The compacted graphite permits strength. Stiffness and ductility that exceeds those of gray iron.

        7.4 Properties of compacted cast iron:

1.      Compacted cast iron to retain good damping capacity, and thermal conductivity.

2.      Its resistance to crazing, tracking and distortion is superior to both S.G. iron and gray iron. As the shrinkage during casting is less than in S.G. iron.

3.      This cast iron having inferior mechanical properties hut similar production costs as S.G. Iron has limited replacement potential to S.G. iron parts. However, because of greater strength and toughness, it can replace more expensive alloyed gray cast irons.                                  Figure 7.1: Core Die (1.3cm dia)                                        

7.5 Apparatus used                                                                                                    

1.      Cast iron power 

2.      Weight balance 

3.     Vernier calipers

4.      Gloves                                                                           

5.      Mask

6.      Hydraulic press                                            

 (a) 7.7 Procedure

First we took total weight 2g cast iron powder and weighted it. Now put this powder in the core die along with spacer.  Then in Hydraulic Press, we have to place the core die on the middle of the bench and push the powder into the core die to compact it. Now by handle move the bottom bench towards upper bench.10, 000-15,000psi pressure applied on the plunger to        move downwards into the die and compact the powder. After sometimes we come out the core die from hydraulic press and then opened the core die thus we can   easily saw compact powder. Now we are using the handle slowly and carefully because compact can be damage if it strikes with the supporting plate. We weighted it again. And find the diameter and height of the pellet by using vernier calipers. And calculate its volume change and then calculate the compact density.                                                                     

                                                                                                     

                                                                                                                                                                                                                                                                                                                                                                      

                                                                                                     Figure 7.2: Hydraulic press (Carver)                     7.8 Observation and Calculation:                                           

Weight of sample	2g
Diameter of sample (d)	1.3cm
Height of sample  (h)	0.437cm
Radius of sample   (r)	0.65cm

Volume (V) = πr2h                                             r=d/2                            =  3.1415*(0.65cm)2 *0.437cm                            =0.58002 cm3 Green density=mass/volume                           =2g/0.58002cm3     Green density  =3.44g/cm3

7.9 Result. Green density of cast iron 3.44g/cm³ are obtained.

                  (b)   Sintering of Compacted Cast Iron  

(b) 7.1 Objective:

The objective of sintering to find out the sintered density of cast iron.

(b) 7.2 Introduction:

Sintering is the process of compacting and forming a solid mass of material by heat or pressure without melting it to the point of liquefaction. Sintering happens naturally in mineral deposits or as a manufacturing process use with metals ceramics plastics, and other materials. The atoms in the materials diffuse across the boundaries of the particles, fusing the particles together and creating one solid piece. Because the sintering temperature does not have to reach the melting point of the material, sintering is often chosen as the shaping process for materials with extremely high melting points

(b) 7.3 Properties:

Sintering is effective when the process reduces the porosity and enhances properties such as strength, electrical conductivity, translucency and thermal conductivity.  It may be useful to increase its strength but keep its gas absorbency constant as in filters or catalyst.

(b) 7.4 Application:

Sintering is one of the final stage of ceramics and it is used to increase the strength of the compacted materials.

( b) 7.5 Apparatus Used:

1.      Compacted MgO powder                                   

(b) Figure 7.1: muffle furnace (Nebertherm)

2.      Compacted mixture powders

3.      Gloves and mask

4.      Tongs

5.      Vernier calipers                                                

6.      Weight balnce  

7.      Muffle furnace                                                                                                                                                                                           

(b) 7.6 Procedure

Green compacted samples or pellets are placed in muffle furnace for sintering. The pellets are heated at 950◦c for 120 mints to each sample which is to be sintered and given a same soaking time 120 mints. We weighted it again after sintering and find out the diameter and height of pellets by vernier caliper. Finally, calc

(b) 7.7 Observation and Calculation:

Weight of sample	2.55g
Diameter of sample (d)	1.3cm
Height of sample  (h)	0.5cm
Radius of sample   (r)	0.65cm

Volume (V) = πr2h                                             r=d/2                            =  3.1415*(0.65cm)2 *0.5cm                                 = 0.663641cm3 sintered density=mass/volume                           =2.55g/0.663641cm3  sintered density      =3.8g/cm3

 

(b) 7.9 Result. Sintered density of cast iron 3.84g/cm³ are obtained.

(a) Compaction of silica and FeO powders.(b) Sintering of compacted mixture SiO2 and FeO powders

 

(a) 6.1 Objective:

The objective of this experiment is to get the green density of powders and their effect on the processing characteristics.

(a) 6.2 Introduction:

Silicon dioxide also known as silica and with the chemical formula of SiO₂ and most commonly found in nature as quartz and in many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and most abundant families of materials, existing as a compound of several minerals and as synthetic product. Notable examples include fused quartz fumed silica, silica gel and aero gels. It is used in structural materials, microelectronics (as an electrical insulator), and as components in the food and pharmaceutical industries. Iron oxides are widespread in nature, play an important role in many geological and biological processes, and are widely used by humans, e.g., as iron ores pigments catalysts in termite and hemoglobin. Common rust is a form of iron (III) oxides. Iron oxides are widely used as inexpensive, durable pigments in paints, coatings and colored concretes. Colors commonly available are in the "earthy" end of the yellow/orange/red/brown/black range. When used as a food coloring

(a) 6.3 Apparatus used: 

1)      Silica and Fe powders                        

(a) Figure 6.2: Hydraulic press (Carver)

2)      Core die            

3)      Carver Hydraulic press

4)      Spacer                     

5)      plunger                                                               

6)      Vernier calipers                       

7)      Gloves

 

(a) Figure 6.1: Core Die (1.3cm dia)

 

 

 

 

                  

(a) 6.7 Procedure:                                                               

First we took total weight 1.5g powder in which 1g silica (SiO₂) and  0.5g FeO and weighted it. We successfully mixed the powders by hand for 5 mints. Now put this mixture of powder in the core die along with spacer.  Then in Hydraulic Press, we have to place the core die on the middle of the bench and push the powder into the core die to compact it. Now by handle move the bottom bench towards upper bench.10,000 Psi pressure applied on the plunger to move downwards into the die and compact the powder. After sometimes we come out the core die from hydraulic press and then opened the core die thus we can easily saw compact powder. Now we are using the handle slowly and carefully because compact can be damage if it strikes with the supporting plate. We weighted it again. And find the diameter and height of the pellet by using vernier calipers. And calculate its volume change and then calculate the compact density.

(a) 6.8 Observation and Calculation:

Weight of sample	1.5g       (1g silica+ 0.5g FeO)
Diameter of sample (d)	1.3cm
Height of sample  (h)	0.401cm
Radius of sample   (r)	0.65cm

Volume (V) = πr2h                                             r=d/2                            =  3.1415*(0.65cm)2 *0.401cm                            =0.5322 cm3 Green density=mass/volume                           =1.5g/0.5322cm3  Green density     =2.8g/cm3

 

(a) 6.9 Result:         

      Green density of 2.8g/ cm³ of silica and FeO are obtained. 

 (b) Sintering of compacted mixture SiO₂ and FeO powders

(b) 6.1 Objective:

The objective of sintering to find out the density of a mixture of TiO₂ and FeO powders.

(b) 6.2 Introduction:

Sintering is the process of compacting solid mass of material by heat without melting it to the point of liquefaction. Sintering happens naturally in mineral deposits or as a manufacturing process used with metals, ceramics, plastics and other materials. The atoms in the materials diffuse across the boundaries of the particles, fusing the particles together and creating one solid piece. Because the sintering temperature does not have to reach the melting point of the material.

(b) 6.3 Properties:

Sintering is effective when the process reduces the porosity and enhances properties such as strength, electrical conductivity, translucency and thermal conductivity.  It may be useful to increase its strength but keep its gas absorbency constant as in filters or catalyst.

(b) 6.4 Application:

Sintering  is one of the final stage of ceramics and it is used to increase the strength of the compacted materials.

(b)    Figure 6.1: Muffle furnace (Nebertherm)

(b) 6.5 Apparatus required:

1.      Compacted mixture powders(TiO₂+Fe)

2.      Gloves

3.      Tongs

4.      Vernier calipers

5.      Weight balance

6.      Muffle furnace( Nabertherm)                                                         

7.      Mask                                                                                                                                                                                                                  

(b) 6.6 Procedure:

Green compacted samples or pellets are placed in muffle furnace for sintering. The pellets are heated at 950◦c for 120 mints to each sample which is to be sintered and given a same soaking time 120 mints. We weighted it again after sintering and find out the diameter and height of pellets by vernier caliper. Finally, calculate the volume and compact density of sintered pellets.

(b) 6.7 Observation and Calculation:

Weight of sample	1.72g
Diameter of sample (d)	1.381cm
Height of sample  (h)	0.43cm
Radius of sample   (r)	0.6905cm

Volume (V) = πr2h                                             r=d/2                            =  3.1415*(0.6905cm)2 *0.43cm                                 = 0.6440cm3 sintered density=mass/volume                           =1.72g/0.6440cm3  sintered density      =2.6g/cm3

 

 

(b) 6.8 Result:

Sintered density of silica and FeO 2.6g/cm³ are obtained at temperature 950◦c.