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Physical Vapor Deposition techniques and influencing process parameters on
coatings
1. Mubarak, A., Hamzah, E., Toff, M.R.M., Hashim, A.H. and Amin, M., (2005), “Review of physical
vapor deposition for hard coatings”,20, pp: 17-18
2. Krishna Valleti , C. Rejin, Shrikant V. Joshi, Factors influencing properties of CrN thin films grown by cylindrical cathodic arc physical vapor deposition on HSS substrates, Materials Science and Engineering A 545,(2012), pp: 155-161
Presented by
D.RATHIRAM NAIK
15MT60R35
IIT KHARAGPUR
M.Tech- 1st year
ContentsIntroduction
Physical Vapor Deposition(PVD)SputteringCathodic Arc PVD
Factors Influencing Sputtering DepositionNitrogen/Argon ratio
Factors Influencing CAPVD coatingsSubstrate roughnessMetal ion etchingPlasma etchingPartial pressure of NitrogenSubstrate temperature and bias voltage
Conclusions
References
IntroductionPhysical Vapor Deposition(PVD):o Sputtering
o Cathodic Arc PVD
Why to prefer PVD:◦ Applications from decorative to high temperature super conducting
◦ Very high deposition rates 25 (μm/sec)
◦ Any type of material we can coat (compounds, metals, alloys, mixtures)
◦ Hard coatings
◦ Resistant to oxidation
DisadvantagesIt generates the less quantity of ionized target atoms than CAPVD
Low ionisation rates
Target poisoning • Deposition rate decreases as Nitrogen partial pressure increases o Nitrogen covering the target
High substrate heating
Influence of factors Steel substrate
Mode:Reactive magnetron sputtering
Reactive gas: Nitrogen
Sputter gas: Argon
N2 / Ar ration = R
As R increasing from 0.1 to 0.7 stress levels in the sample is increases
R on mechanical propertiesNitrogen occupies interstitial positions and buildup the stress TaN is in unstoichiomatric conditiondue to this hardness is going to increases
After reaching stoichiometric after R= 0.5hardness (~40 GPa) is going to decreases
Cathodic Arc PVD Evaporative technique
Used to deposit single and multilayer coatings
Ceramic, metallic, alloys, compounds coatings
High energy input than the PVD sputtering
It generates the highest quantity of ionized targetatoms 50-100%
Highest ionisation rates leads to high deposition rates
Highest adhesion properties
High energy ions removes oxide layers if present
Creation of roughness but it is in atomic levelroughness
Process in CAPVDSOURCE
(Solid / Liquid)
GAS PHASE
SOLID PHASE(Changes in physical morphology)
Evaporation
Transport &
Deposition
CAPVD Unit at ARCI - HYD
REF: [3]
Main components of CAPVDDOOR CATHODES
Al
Cr
Ti
CENTRAL CATHODEAlSi+
PRESSURE GAUGESRotor pumps---- 1X10-3 mbar
Turbo Molecular--1X10-7 mbar
CAROUSEL
Advantages of CAPVDSimple process,
Highly pure thin films obtained
Most popular method for applying hard coatings in tool industry.
Better uniformity
Good surface finish.
Environmentally clean process
High deposition rates
The low voltage power supplies will not damages the target materials.
High vaporization rates are obtained
Disadvantages of CAPVD Formation of macro particle
Excess atoms that are not completely ionized these neutral atoms leads to formation of macro droplet
Material wastage is more in the chamber
Difficult to stabilize Arc
Difficult to evaporate alloys due to different melting points
Only four cathodes are present
Comparison between CAPVD and sputteringFEATURE CAPVD SPUTTERING
Plasma density, m3 1016 - 1020 1014-1018
Ion velocity , m/s (1-2)x104 (3-6)x103 (Ar ions)
Ion energy, eV 50-150 10-40
Macro particle Yes No
Electrical Characteristics High current (Iarc = 30-500A)Low voltage (10-50V)
High voltage (V= ~ 1 KV)Low current (10-2 – 1 A)
Influencing process parameters CAPVD SPUTTERING
Target composition Target composition
Substrate temperature Substrate temperature
Bias voltage Substrate bias voltage
Gas flow rate Ion current density
Ion bombardment rates Ion current density
Choice of base material Choice of base material
Influence of parameters
Substrate roughness of HSS:Inverse relation in between adhesion
strength and surface roughness
Decrease in adhesion strength
So, critical load also decreases
Maximum tensile stress between stylus andcoating
Metal EtchingEtching in CAPVD CrN coatings• Type of metal• Ti (MP = 1933 K) or Cr (MP = 2143 K)
• Time of etching
Reduction in droplet formation with Cr thanTi• Due to difference in Melting Point(M.P)
• Higher the M.P smaller the M.P at cathode
• So lower the micro droplet formation
Etching time
Initially removal oxide layers, dust are removed
Surface damage after 15 minutes
Effect of Ar+N2 Ion etching on surface roughness of cutting tools
Process parameters for Ar+N2 Etching at 100 V, 200 V, 300 V
Parameter Values
Bias voltage 100, 200, 300 V
Chamber temp. 465 0C
Process time 05 min
Argon flow rate 200 sccm
Nitrogen flow rate 20 sccm
High Speed Steel:With respect to bias voltage change in roughness decreases
WC-Co sample:With respect to bias voltage change in roughness increasesDue to grain refinement
Influence of Nitrogen partial pressure (Np)Np (varied over the range (i)5×10−3 – (ii)5×10−2 mbar) on CrN. The grown film exhibiteda dense columnar structure with a defect freesubstrate to coating interface
Stresses development in coatings are less
As Np increases compressive stresses aredecreasing
At (i) Nitrogen occupies interstitial position ofCr and build up stress later at (ii) leads toformation of nitrides
Enhancement in adhesion and crackpropagating resistance(CPR)
Influence of substrate temp. and bias voltage An increase in Tsub 2000 C to 5000 C:
• Formation of droplets
• 50 % fall in corrosion resistance
• 30% increase in adhesion strength
• Increase in defect concentration
Increasing the negative bias Voltage(-50 to -150 V): • Increase in adhesion strength about 30%
• Highly dense close packed orientation in (111)
The columnar grain size (column width) increases with increase in TSub but decreases with increasing VSub
Contd…..! Mechanical Properties:• Decrease in hardness with increase in either TSub or Vsub
• Phase composition and strain energy associated with the films
Correct temperature:• Tsub / Tcoating.melt = 0.3
Conclusions Physical vapor deposition techniques were studied with various influencing parameters
Appropriate recipe gives good mechanical , thermal , corrosion and wear resistance properties
Influencing parameters changes process to process and depending on coatings
Influencing parameters depends on substrate materials
References[1]. Krishna valleti, (2009), “Studies on hard TaN thin film deposition by R C-Mag technique”, J. Vac. Sci. Technol. A 27, 626
[2]. Lin, K.L., Hwang, M.Y. and Wu, C.D., (1996), “The deposition and wear properties of cathodic arc plasma deposition TiAIN deposits”, Mater. Chem. Phys. 46, pp. 77–83.
[3]. Mubarak, A., Hamzah, E., Toff, M.R.M. and Hashim, A.H., (2005), “The effect of Nitrogen gas flow rate on the properties of TiN-coated HSS using Cathodic Arc Evaporation PVD Technique”, Surface Review and Letters, 12, pp. 631-643.
[4]. Zlatanovi , M., (1991), “Deposition of (Ti,Al)N coatings on plasma nitride steel”, Surf. Coat. Technol., 48, pp. 19–24.
[5]. Krishna Valleti , C. Rejin, Shrikant V. Joshi, Factors influencing properties of CrN thin films grown by cylindrical cathodic arc physical vapor deposition on HSS substrates, Materials Science and Engineering, A 545, (2012), 155-161
[6]. J.D. Kamminga, P. Van Essen, R. Hoy, G.C.A.M. Janssen, Tribol. Lett. 19 (2005), 65–72.
Contd…![7].M. Cekada, P. Panjan, D. Kek-Meri, M. Panjan, G. Kapun, Vacuum 82, (2008),252–256.
[8]. J.A. Thornton, D.W. Hoffman, Thin Solid Films 171 (1989) 5–31.
[9] P.A. Lindfors, W.M. Mularie, Surf. Coat. Technol. 29 (1986) 275–290.
[10] S. Zhang, D. Sun, Y. Fu, H. Du, Surf. Coat. Technol. 198 (2005) 74–84.
[11] W.K. Grant, C. Loomis, J.J. Moore, D.L. Olson, B. Mishra, A.J. Perry, Surf. Coat. Technol. 86–87 (1996) 788–796.
[12]. K Valleti, A Jyothirmayi, M Ramakrishna, SV Joshi, Influence of substrate temperature and bias voltage on properties of chromium nitride thin films deposited by cylindrical cathodic arc deposition, Journal of Vacuum Science & Technology A 29 (5), 051515
[13]. Q. M. Wang and K. H. Kim, J. Vac. Sci. Technol. A 26, 1258 (2008).
AcknowledgmentsI would like to thank Mr. N. Ravi (Scientist-E), Dr. Krishna Valle (scientist –D) and Mr. PuneetChandran(research scholar) department of Center for Engineered Coatings, InternationalAdvanced Research Centre for Powder Metallurgy and New Materials (ARCI) – Hyderabad
I would like to thank International Advanced Research Centre for Powder Metallurgy and NewMaterials (ARCI) – Hyderabad
THANK YOU
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