ISSN: 2454-1362, An ... · components can be manufactured by using powder metallurgy. It comprises blending of the material, fine powders, with lubrication such as wax, graphite and

Imperial Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-11, 2016 ISSN: 2454-1362, http://www.onlinejournal.in

Imperial Journal of Interdisciplinary Research (IJIR) Page 1050

An Experimental Study of Effect of the Parameters of HVOF Coating of WC-10Co-4Cr

on Mild Steel Plate

Vikash Kumar Pandey¹ & Antariksha Verma² Suresh Gyan Vihar University ¹ ²

Abstract: Thermal spray coating is one of the most important methods of enhancing the material properties of the base metal by coating with powder metal. In this paper the experiment was conducted with the metal powder of WC-10Co-4Cr. The HVOF spray method is selected in this research and the mild steel plate was taken as the base metal. Basically four parameters have been used, they are- oxygen flow rate, LPG flow rate, standoff distance, powder feed rate. Various testing measures have been taken for the final result. Micro-hardness test, porosity level, optical microscopy, SEM image analysis were performed at testing centre. After these analyses it was found that the hardness increased at high level and the porosity level is upto 1 %. Uniform coating showed by optical microscopy and SEM image analysis.

Keywords: HVOF spray, porosity, micro-hardness, SEM, optical microscopy, mild steel plate.

1. INTRODUCTION: Metal casting is one of the direct methods of manufacturing the desired geometry of component. The method is also called as near net shape process. The principle of manufacturing a casting involves creating a cavity inside a sand mould and then pouring the molten metal directly into the mould. Casting is a very versatile process and capable of being used in mass production. The size of components is varied from very large to small, with intricate designs. 1.1 POWDER METALLURGY TECHNIQUE: Powder metallurgy is the process whereby metallic shapes are manufactured from metallic powders.

Fig.1. Process Flow

1.2 NECCESSITY OF POWDER METALLURGY

Due to the following reasons:-

1. Difference in melting temperatures of two elements is so much that one would become gas before the other has melted.

2. Melting and solidification causes poor quality.

3. Melting causes loss of identity of the constituents.

4. Some metals do not form a liquid solution and thus can’t be alloyed to produce special properties.

2. RESEARCH METHODOLOGY: In metal casting, the pouring of molten metal is processed in the cavity and mould of the desired shape and then allowing it to solidify. After that when it is removed from the mould, the casting is not of the same size as the mould. After that solidification starts and then it is kept for cooling. In the metal casting, so many defects arises during casting due to the improper pouring of molten metal these are arises. The defects may be due to contraction of metal, air permeability etc.

http://www.onlinejournal.in/




By using metal powders, the large no. of components can be manufactured by using powder metallurgy. It comprises blending of the material, fine powders, with lubrication such as wax, graphite and others. After that pressing of the die with external forces and then compacting and heating of the compressed material. In powder metallurgy the porosity level is 5-10 %.

Powder metallurgy is best suited method for the production of the precision materials of accurate dimension. This method is more important as compared to others. There are following reasons to choose this method:-

1. As compared to die casting, the powder metallurgy produces more accurate dimension precision equipments and elements. In the die casting the casted material cannot have accurate shape and size as per requirements.

2. Powder metallurgy component have more strength, wear resistance or high temperature resistance as compared to the other manufacturing process, such as sand die casting, investment casting, permanent die casting.

3. As compared to the investment casting the tooling cost is not more for the powder metallurgy.

4. As compared to the foundry casting, powder metallurgy offers greater precise, eliminating most of the machining process.

To solve the problem arises in the casting we have used powder metallurgy technique to reduce the casting defects and the casting cost, because it reduces the manufacturing time and process. For the observation of the defects we have used different testing parameters such as SEM, MRI, and microscopy. To find the cause of the defects we have used root cause and effect diagram to find out the possible reasons of the defects in the casting.

2.1 MATERIALS AND METHOD

This chapter describes the materials, equipment and methodology equipment employed to carry out the research. The methodology involved had three parts:

1) Characterization of various powders used during thermal spray coating process;

2) Coating deposition;

3) Characterization and testing of coatings.

2.1.1. Stainless steels Stainless steel is steel alloyed with chromium. In order for steels to be classified “stainless”; here must be an addition of at least 11 wt. % of chromium (Lo et al., 2009). At this Cr level, stainless steels develop their corrosion resistance characteristic from the formation of a thin passive film (chromium oxide) with the thickness layer of less than 10 nm on the surface. This passive film then prevents surface corrosion and inhibits corrosion from spreading into the metal’s microstructure; however abrasion can lead to the local deterioration or complete removal of this film (Lo et al., 2009).

Aggressive mining environments exacerbate the exposure of steel to pitting and rusting. In order to protect steel in these environments the amount of Cr added to the steel must be increased proportionally. While the Fe–Cr system forms the basis, modern stainless steels, besides Cr, also contain a host of other alloying elements whose presence improves specific properties. Mo is added for improving resistance against pitting and Ni for stabilizing the austenite phase. When the contents of Cr and Ni are added in substantial amounts, the resulting alloy is called heat-resisting alloy. Although a number of alloying elements may be present in stainless steels, their total content is usually kept below the iron content, in order to maintain the resulting alloy steel (Lo et al., 2009).

2.1.2 Surface Engineering In order to improve the material properties of stainless steels used in mining applications, surface engineering plays a crucial role. Surface engineering is defined as the branch of science that deals with methods for achieving the desired surface requirements and their behaviour in service for engineering components. The surface of any component may be selected on the basis of texture and colour, but engineering components must perform certain functions completely and effectively, under various conditions in aggressive environments (Mulligan et al., 2008). Present surface engineering research is focussed on depositing hard phases such as carbides and corrosion resistant metal binders.

2.1.3Thermal spray technology Thermal spray is one of the surface engineering technologies that offer the potential to improve component lifespan. Thermal spray describes a group of coating processes used to apply metallic or non-metallic coatings. These coatings are grouped into three major categories: flame spray, electric arc, and plasma arc spray (ASM International, 2004). This process is known for producing high bond strength coatings with





minimum porosity, thermal spray process can also be attractive with respect to reducing maintenance costs as well as decreasing plant downtime (Souza and Neville, 2005). such as Cr and Ni with the aim of improving adhesion between carbides and binders and therefore achieving a successful combined effect of corrosion and wear resistance (Burakowski et al., 1999; Wood, 2007).

Thermally sprayed ceramic coatings on steel represent an efficient and cost- effective way of improving the wear resistance of mechanical components, when common thermal treatments (such as quenching and tempering) or thermo-chemical processes such as carburizing, nitriding prove to be insufficient (Monticelli et al., 2011).

2.1.4High Velocity Oxygen Fuel (HVOF) According to Wood, (2010) there is an increased demand in engineering applications for composite coatings that not only protect the substrate from mechanical damage, but also improve the corrosion and wear resistance.

HVOF thermal spraying technology has been applied to successfully produce superior bond strength, high density coatings with relatively low decarburization due to the high particle velocities and relatively low particle temperatures induced in the deposition process. The process is a low temperature method 15 compared with other techniques, it requires minimal base metal preparation and it can be directly applied to the working tools. HVOF is generally used when high hardness as well as low friction coatings is required to fight against material deformation and mass loss, there is less force acting on the surface of a component, and hence, less energy is dissipated as heat (Wood, 2010). The HVOF technology has developed over the years, it is now producing coatings with better compaction and low chemical decomposition, especially for WC based coatings. The beneficial property of the HVOF process is the low temperatures involved, and the higher velocity reached by particles which minimizes any potential damage to the coating and substrate (Souza and Neville, 2005). When compared to other processes such as plasma spraying, HVOF is considered an effective process for depositing cermet coatings with low porosity content of (about 1%), it allows creating denser and less oxidized coatings with no significant thermal and mechanical alterations of the substrate (Fredizzi et al., 2007). HVOF thermal spraying is a technique whereby powder material is melted and propelled at a high velocity towards a surface; where sprayed particles impinge on the target substrate often in the semi-molten state and pile up to form a coating (Ishikawa et al., 2004). The system consists of a Diamond Jet (DJ) gun;

powder feed unit, flow meter unit, and an air and gas supply unit. The powder feed unit is comprised of a hopper assembly, air vibrator, feed rate meter, and control cabinet. The desired powder is fed from the powder feed unit by means of a carrier gas to the gun where combustion occurs. The amount of powder required for deposition may be regulated using the powder feed rate meter. The HVOF thermal spraying system uses oxygen and propylene as the combustion gas, along with compressed air. In the combustion zone, the powder material enters the flame, where it becomes molten or semi-molten, depending on the melting temperature and the feed rate of the material. The flame temperature for the HVOF process is between (2300–3000oC). The molten or semi-molten particles are then propelled out of the gun nozzle at supersonic velocities of over 550 – 850 m/s towards the die where the material deposits (Mulligan, Smith, & Stokes, 2008).

Fig 2. shows a schematic diagram of thermal spray coating process with liquid fuel.

2.1.5 Powder preparation technology The two main spray powder preparation technologies are ‘sintering and crushing’, and ‘agglomerating and sintering’. Sintered and crushed WC based spray powders, which entered the market during recent years, are characterized by a controlled carbon content, assuring constantly high cobalt feedstock powders prepared by agglomeration (via spray drying) and subsequent sintering (Berger, 2007). These powders exhibit improved flowability, a homogenous microstructure for all powder particles, a controlled hard phase grain size and the predominance of equilibrium phases (Berger, 2007). ‘Agglomerating and plasma densification’ technology is another technology that was introduced into industrial practice to enhance flowability, but high temperature has effects on the phase composition and microstructure of hardmetal composition during plasma spraying. In such powders, high temperature and non-equilibrium phases are commonly observed (Berger, 2007). Since the early stages of thermal spray process, it has been recognized that the powder composition, size distribution, shape, mass density, mechanical





resistance, components distribution for composite particles play a key role in coating microstructure and thermo-mechanical properties. The principal characteristics of particles are strongly linked to the manufacturing process (Fauschais et al., 2009).

2.1.6 Cermets Cermets or sintered metal ceramics are defined as materials obtained by the combination, in different ways, of ceramic material with metals (Davies, 2001). The ceramic components are usually oxides, carbides, borides, nitrides, silicides and sulphides. Mostly used are heat resistant and refractory cermets and those resistant to quick changes in temperature. These are carbides of tungsten, chromium, titanium, molybdenum, zirconium, hafnium, vanadium, niobium and tantalum; nitrides of titanium, vanadium, zirconium, niobium, hafnium, tantalum, tungsten, chromium and molybdenum; borides of titanium and zirconium; silicides of molybdenum and tungsten. Also used are mechanical mixtures of the above, as well as ternary and quadruple compounds, e.g., titanium carbonitride or titanium alumino nitride (Davies, 2001). Frequently cermet coatings consist of WC or Cr3C2 particles embedded in a metal binder, which can be a pure metal or a mixture consisting of Ni, Cr or Co (Wood, 2010). These cermets increase the wear resistance of the mechanical components, while limiting the production cost (Berger, 2007; Montecilli, 2010). Traditionally most important cermets compositions for coating applications are WC–12Co, WC–17Co, WC–10Co–4Cr, WC–12Ni WC–20CrC–7Ni and Cr3C2–20NiCr (Berger, 2007). According to Berger, (2007) the majority of commercially available materials consist of metallic binder phase amounting in the range of (20–30 vol. %). Due to differences in hard phase densities, this results in amounts of 12–17 wt. % binder for WC–Co and 28–37 wt. % for TiC based hardmetals. The main parameters influencing the tribological properties of these coatings are carbide volume fraction and grain size. Usually, an increase in carbide volume fraction reduces the coating wear rate. However, on the contrary contrasting results are obtained on the influence of the grain size; often nano structured WC–Co coatings with small grain size possess lower sliding wear resistance than conventional powders (Montecilli et al., 2010). The selection of coating material should be guided by the environment the coatings will be used in. In fact, in corrosive media the wear resistance of ceramic–metallic coatings strongly depends on the corrosion resistance of the metallic binder. WC–Co cermets undergo a significant corrosion attack dominated by Co phase dissolution, except in alkaline electrolytes where dissolution of WC is also important (Montecilli et al, 2010). Several efforts have been made to

reduce the corrosion susceptibility of cermets by modifying the cermet composition. It was found that using Ni instead of Co as a binder material or alloying Ni into the Co binder phase leads to a higher corrosion resistance. But the negative consequence is that the mechanical properties deteriorate (Montecilli, 2010). Cr alloyed to Co as in WC–Co-Cr or WC/CrC–Co-Cr coating does not afford passivity and extensive carbide/matrix interface attack is detected in neutral chloride solution on the contrary, both WC–Cr-Ni and Cr3C2–NiCr coatings exhibit passive conditions and low corrosion rates (Montecilli, 2010).

ELEMENT COMPOSITION (wt % ) Si 0.42

Mn 0.70-0.92 C 0.15-0.19 P 0.042 Ni 0.00 S 0.043 max

Mechanical properties

PROPERTIES MEASUREMENTS Hardness (HRB ) 141-170 HV

Elastic modulus (GPa ) 375 Tensile Strength (MPa ) 400-560 n/mm2

Poisson’s ratio 0.25-0.38 Yield strength ( MPa ) 300-441 n/mm2

Elongation ( % ) 10-14 %

Fig 3. Flow Chart Of Powder Preparation.





COMPARISON OF THE THERMAL COATING TECHNIQUES:-

PARAMETERS AS FS HVC

W HVOF

Spray System Tafa 9000

Metco 10E

HVw 2000

HIPOJET 2700

Wire Diameter (mm) 1.59 3.18 1.59 --------------

-- Wire/powder

Feed Rate (m/min

0.46 ----- 1.59 37.5 (g/min)

Spray Distance (mm) 153 137 158 325

Fuel Gas (bar/l/min) --- Acetylen

e / 19

Propane

3.9/22

Propane 4.1/ 22

Oxygen (bar/l/min ) ---- 145 4.2/10

3 254-350

(lpm) Compressed air

(bar/l/min ) 4.2/52

8 5.3 /776 6.5/662 7.3/ 825

Chamber pressure (bar) ------ ------ ----- Upto 24

Current ( A ) 150 165 150 110 Potential ( V ) 30 65 65 72 Temperature

(c) 2500 to 3000

Metal deposition rate

(m/s) 731 812 837 932

Where AS- Arc Spray, FS- Flame Spray, HVOF- High velocity oxy Flame Spray, HVCW- high velocity wire combustion spray. 2.2 MICRO STRUCTURE CHARACTERSTICS:- PARAMET

ERS AS FS HVCW HVOF

Thickness (µm) 289±17 271±19 310±30 329±20

Grit Size (µm) --- 35 63 23

Roughness (µm)

14.8±1.5

14.5±0.7

13.8±1.3

10.6±0.3

Mass loss(mg) 111.5 106.5 102.6 84.3

Oxygen content (wt

%

4.27±0.12

1.88±0.03

8.59±0.29

12.05±1.8

Hardness ( HV0.3)

316±43 393±46 487±39 759±56

Porosity (vol % ) 4.1 3.4 3.0 1.5

Bond Strength (MPa )

40.2±2.2

55.9±4.6

39.72±3.5

89.6±4.5

2.3 THERMAL SPRAY EQUIPMENT HIPOJET 2700:- In thermal spray coating machine the material is feed into the form of wire, powder and rod and feed into the flame produced by combustion of gases through spray gun. The fuel used in it are kerosene, propane, propylene, methane gas, natural gas etc.

Fig. 4:- HIPOJET 2700.

HVOF HIPOJET 2700 THERMAL SPRAY SPECIFICATIONS:-

GUN AUTOMATIC MANUAL HIPOJET-2700A HIPOJET-2700M

WEIGHT 1.7 Kg (3.74 lb ) 1.85 Kg ( 4.07 lb ) GASES OXYGEN,

LPG/PROPANE, NATURAL

GASES, AIR

OXYGEN, LPG/PROPANE,

NATURAL GASES, AIR

CONTROL PANEL

AP-2100 MP-2100

DIMENSION 969*597*256 mm 871*502*137 mm WEIGHT 45.2 Kg (98.7 lb ) 38.6 Kg ( 84.6 lb )

ELECTRICITY 220 V/ 1 P/ 50/ 60 Hz

220V/1P/50/ 60 Hz

CONTROL PANEL

AP-2100 MP-2100

DIMENSION 969*597*256 mm 871*502*137 mm WEIGHT 45.2 Kg (98.7 lb ) 38.6 Kg ( 84.6 lb )

ELECTRICITY 220 V/ 1 P/ 50/ 60 Hz

220V/1P/50/ 60 Hz

GAS FLOW ( LPM ) OPERATING PRESSURE

OXYGEN 249-354 10.2 Kg/cm2 LPG/ PROPANE 63-84 069.2 Kg/ cm2

AIR 598-710 069.2 Kg / cm2

METAL POWDER USED

METAL POWDER

SPRAY RATE

DEPOSIT EFFICEINCY

WC-12Co 42 gm / min 75 % WC-17 Co 39 gm / min 62 %

WC-10 Co- 4 Cr 37 gm / min 76 %

Cr3C2 – NiCr 26 gm / min 59 % HVOF POWDER USED:- COMPOSITION DESCRIPTION SIZE

WC -12 % Co AGGLOMERATED , SINTERED

46 ± 13 µm

WC – 17 % Co AGGLOMERATED , SINTERED

46 ± 13 µm

WC – 10 % Co – 4 % Cr

AGGLOMERATED , SINTERED

46 ± 13 µm

Cr3C2 – 20 % NiCr AGGLOMERATED , SINTERED

46 ± 13 µm

WC – 20 % Cr – 7 % Ni

AGGLOMERATED , SINETERED

46 ± 13 µm

NiCrBSi GAS ATOMIZED 46 ± 13 µm

INCONEL STEEL GAS ATOMIZED 46 ± 13





µm

STELLITE – 6 GAS ATOMIZED 46 ± 13 µm

Ni – 20 % Cr GAS ATOMIZED 46 ± 13 µm

2.4 THERMAL SPRAY COATING PROCESS :- In thermal spray coating, first of all the substrate material is collected. After that the powder material WC-10CO-4Cr is prepared by agglomerated or sintered process of grit size of 46 ± 13 µm. The coating process is carried out by HVOF HIPOJET 2700 spray gun at ALLOY SPRAY AND ENGG at AHMEDABAD GUJRAT.

Following are the major steps involved:-

1. In the powder feed mechanism the powder of WC-10CO-4Cr is feed in it of grit size 47 µm.

Fig.5 :- powder feeder.

2. After that the oxygen and LPG are choose as the fuel and gas for the mechanism. The ratio of the fuel-gas are adjusted by using control panel according to the process.

Fig.6 :- Control panel for fuel gas ratio adjustment.

3. After that the material pieces are collected and kept on the standing table so that it would be easy to do the experiment.

Fig.7 :- standoff distance b/w work piece and gun.

4. After the final adjustment of the standoff distance the supply of the powder from the powder feeder and ignition of the nozzle starts.

Fig.8 :- Coating process.

4. After coating process large no. of samples collected for the testing. The varying parameters are the spray standoff distance, oxygen flow rate, acetylene flow rate and the thickness of coating.

Fig .9 :- samples of coated materials.





2.5 EXPERIMENTATION CALCULATION

1.1 Testing of Coated Powder on Substrate material:-

Microstructure of the coating on substrate metal plate.

Microhardness of the coated material on M.S plates.

Porosity volume % fraction testing. Scanning Electron Microscopy Coating Thickness measurement.

The coating testing parameters that were taken are as follows:-

Standoff Distance Oxygen flow rate LPG flow rate Powder flow rate.

The experimental procedures were as follows:- SAMPLE NO.

STANDOFF

DISTANCE(inch)

OXYGEN FLOW RATE(m

3/min)

LPG FLOW

RATE(m3/min)

POWDER FEED RATE(gm/min)

1 7 180 70 14.09 2 7.7 265 64 14.09 3 8.5 35 58 14.09 4 7.7 180 58 15.94 5 8.5 265 70 15.94 6 7 350 64 15.94 7 8.5 180 64 17.80 8 7 265 58 17.80 9 8.5 350 70 17.80

3. RESULT AND DISCUSSION SAMPLE NO. COATING THICKNESS

MEASUREMENT(µm) 1 221 2 175 3 170 4 184 5 173 6 172 7 264 8 275 9 252

TEST:- MICROSTRUCTURE EXAMINATION

TEST METHOD:- TCRADVTM-14, E-407-07

TEST PERFORMED TCR ADVANCE ENGG.PVT LTD.

INSTRUMENT USED OPTICAL MICROSCOPE

NATURE OF SAMPLE TEST PIECE- 50x50x5mm

SPECIFICATION HVOF COATING OF WC-10Co-4Cr

ETACHENT USED MURAKAMI’S REAGENT

Fig.10.SEM at 270X with 50 µm particle size.

Fig.11. SEM of the coating at X100 grit size of 100 µm.

3.1 MICRO- HARDNESS TEST OF THE COATING:

FOR SAMPLE 1:-

AT CROSS SECTION

Micro- hardness of coating at 300gms. Load (HV0.3)

1 2 3

LOCATION 1 765 686 664

LOCATION 2 689 710 725





LOCATION 3 575 608 645

AVERAGE 674.1

FOR SAMPLE 2:-

AT CROSS SECTION


1 2 3

LOCATION 1 594 578 610

LOCATION 2 524 556 589

LOCATION 3 619 626 687

AVERAGE 598.1

FOR SAMPLE 3

AT CROSS SECTION


1 2 3

LOCATION 1 627 731 718

LOCATION 2 689 710 787

LOCATION 3 664 678 709

AVERAGE 701.40

FOR SAMPLE 4

AT CROSS SECTION


1 2 3

LOCATION 1 864 959 960

LOCATION 2 998 1002 930

LOCATION 3 810 889 926

AVERAGE 926.40

FOR SAMPLE 5:-

AT CROSS SECTION


1 2 3

LOCATION 1 768 789 809

LOCATION 2 724 746 796

LOCATION 3 805 776 809

AVERAGE 780.2

FOR SAMPLE 6:-

AT CROSS SECTION


1 2 3

LOCATION 1 654 668 696

LOCATION 2 780 746 748

LOCATION 3 658 740 719

AVERAGE 712.10

3.2 VOLUME FRACTION OF % POROSITY:

SAMPLE 1:-

FRAME % POROSITY 1 1.85 2 1.19 3 2.38 4 1.07 5 1.35

AVERAGE 1.57

SAMPLE 2

FRAME POROSITY 1 1.32 2 1.60 3 1.92 4 1.67 5 1.38

AVERAGE 1.59





SAMPLE 3:-

FRAME % POROSITY 1 2.70 2 2.98 3 2.21 4 1.58 5 0.79

AVERAGE 2.05

3.3 EFFECTS OF DIFFERENT PARAMETERS ON COATING PROPERTIES:- 1. Graph between Micro-hardness and coating thickness:- From the graph plotted it was found that as the coating thickness increases the micro- hardness of the coating also increases.

Fig.12. Graph between coating thickens and micro-

hardness. 2. Graph between coating thickness and oxygen content:- From the graph it was found that as the oxygen content or rate of flow increases the coating thickness decreases. But above 430 m3/min the coating not possible.

Fig.13. Graph between coating thickness and oxygen content.

3. Graph between porosity and oxygen content: - As the oxygen content increases the porosity also increases. It can be very well illustrated by the table of calculated porosity.

Fig.14. Graph between porosity and oxygen content.

4. Graph between porosity and LPG flow rate:-

Fig.15. Graph between porosity and LPG flow rate.

5. Graph between standoff distance and coating thickness:-

Fig.16. Graph between standoff distance and coating

thickness

6. Graph between powder feed rate and coating thickness:-





Fig.17. graph between powder feed rate and coating

thickness. 7. Graph between powder feed rate and micro-hardness:-

Fig.18. Graph between powder feed rate and micro-

hardness. 8. Graph between LPG and micro- hardness:-

Fig.19. Graph between LPG flow rate and

micro- hardness.

4. CONCLUSION After completing the experiment on the M.S metal plate having dimension of 50x50x5mm of coating done by HVOF technique. After concluding the result it was found that the coating of the powder on the substrate material of having low strength and

high corrosive rate can be increased by this process.

The coating thickness was found after testing of average of 275 µm. The micro- hardness was calculated between 678.10 to 928.10 HV0.3.

The porosity of the coating was found low as compared to other thermal spray coating. It was found approx. 1.45 that was very good by HVOF technique.

The microstructure image, SEM image showed that the coating is of having uniform thickness and less voids are present in it.

5. REFERENCES:

[01] kumar.s & houldy “ the continuous casting of stainless steel.” infocon 6. proceedings of the 1st international chromium steel and alloy congress, capetown. vol.2, (1992), page no.7-23. [02] kang yonglin “metallurgical quality of csp thin slabs’” jrnl. of university of science and technology, biejing, vol.11, no.2, (2004), 106.

[03] kurz. w “about initial solidification of continous casting steel.” la metallergia italiana 2008, no. 7/8 , 56-64, [04] t.t. jung “micro structure and properties of ti-8mo-12fe and ti-8mo-8cu alloys with cr3c2 additives produced in powder metallurgy process”. jrnl. no.-36, (2012), 368-373 page no., elsevier ltd. [05] e.o.mostafa “ mold thermo – mechanical rigidity criterion for surafce quality of continuous casting of steel.” material sciences and applications, (2013),4, 39-51, scrip journals. [06] s.k.mohan, “evaluation of fracture toughness and mechanical properties of alumunium alloy 7075, t6 with nickel coating.” gcmm 2014, procedia engg. 97, (2014), 178-185. elsvier ltd. [07] labisz.k “fatigue behaviour of sintered duplex stainless steel.” 17th international colloquium on mechanical fatigue of metals, procedia engg. 74, (2014), 421-428, elsevier ltd.

[08] rajkolhe rajesh, “defects, causes, and their remedies in casting process: review.” international journal of research in advent technology, vol. 2, no.-03, march 2014.





[09] md. ashif, “improved mechanical properties of magnesium based composites titanium- aluminum based hybrids.” journal of magnesium and alloys, (2015), page no. 1-9.elsevier ltd.

[10] gartner. f, “influence of process parameters on the quality of thermally sprayed x46cr13.” cobef 2003- 2nd brazilian manufacturing congress 18-21 may 2003 , vol-26, no-1, 2004.

[11] santana.y.y, “ mechanical properties and microstructre of wc-10co-4cr and wc-12co thermal spray coatings deposited by hvof.” surface engg. vol-2, no-1, july 2008.

[12] bonara.r.g, “fatigue in aisi 4340 steel thermal spray coating by hvof for aeronautic application.” procedia engg. 2(2010), page no- 1617- 1623. by elsevier.

[13] cinca nuria, “comparison of mechanical and tribological properties of tic-niti and tic-tib2-niti coating.” physics procedia 10 (2010), page no- 65-68, by elsevier.

[14] bonora r.g, “evalaution of wc-10ni thermal spray coating with shot peening on the fatigue strength of the aisi 4340 steel.” procedia engg. 2(2010), page no. 649-656, by elsevier.

[15] houdokova saraka, “ friction properties of hvof sprayed hardmetal coating.” roznov pod radhostem, ceska republika, vol-05, no- 18, year- 2010.

[16] dosta serga, “wear and corrosion of metal matrix (stainless steel or niti ) – tic coatings.” physics procedia 10 (2010), page no- 77-80, by elsevier.

[17] chawla vikas,“thermal sprayed cnt reinforced nanocomposite coating- a review.”journal of minerals and materials charcterization & engg. vol-10, no-08, pp- 717-726, 2011.

18] suhonen tomi, “ optimization and characterization of high velocity oxy-fuel sprayed coatings: techniques, materials, and application.” coatings, issn-2079-6412, page no- 17-52, year- 2011.

[19] ghajali m.j, “effects of plasma spray parameters on tio2 coated mild steel using doe approach.” ceramics international 39, (2012), page no- 3121-3127. by elesvier.

[20] ni liyong, “effects of surface modification on thermal cycling lifetime of thermal barrier coating with hvof nicraly bond coat.” progress in natural

science: materials international 22(3) page no.- 237-243, year-2012, by elsevier.



Documents

ISSN: 2454-1362, An ... · components can be manufactured by using powder metallurgy. It comprises blending of the material, fine powders, with lubrication such as wax, graphite and