The Wear Resistance of Thermal Spray The

Tungsten and Chromium Carbides Coatings [M.W. Richert. (2011)]

ENMT800202 – Proses Pelapisan & Inhibisi

S2 – Peminatan Korosi

Departemen Teknik Metalurgi dan Material

FTUI 2012

A B Joe H

0806331355

PRESENTATION CONTENT

• Introduction

• Experimental Basis

• Investigation Results

• Conclusion

PLASMA SPRAY

• Plasma spray merupakan bagian dari thermal spray.

• Pada dasarnya proses plasma spray adalah

penyemprotan molten atau heat softened material ke

permukaan untuk memberikan lapisan.

Plasma Spray Schematics

• Plasma Gas: Argon,

Nitrogen, Hydrogen,

Helium.

• Thermal Plasma Heat

Source: Direct Current

(DC) Arc or Radio

Frequency (RC)

Discharge. With T

over 8000K.

• Melting Temperatur:

300 K.

• Base material

combination can be

tailored to provide

unique surface

characteristic.

High Velocity Oxy-Fuel (HVOF)

• HVOF merupakan bagian dari thermal spray.

• HVOF adalah dry process yang menghasilkan lapisan

logam padat yang memiliki sifat fisik yang sama atau

lebih dari Hard Chrome Plating (HCP).

High Velocity Oxy-Fuel (HVOF)

Schematics

• Fuel: propylene,

hydrogen, propane,

kerosene in

combustion chamber.

• Carrier gas: argon.

• Speed: 3000-4000

ft/sec.

• Metal powder: nickel,

nichrome, inconel,

chrome carbide, and

tungsten carbide.

• Uniform coating

thickness: up to 0.250

inches.

COMPARISON

PLASMA SPRAY HIGH VELOCITY OXY-FUEL (HVOF)

• Larger Porosity

• Higher tensile strength

• Better wear properties

• Improved corrosion resistance

• Dielectric and oxide free

• Much cleaner than thermal spray

• Wear Resistance

• Corrosion Resistance

• Low Oxide Content

• Low Stress

• Low Porosity

• High Bonding Strength to Base

Metal

• High Hardness

• Small Microstructure/ nanograins

EXPERIMENTAL PROCEDURE

RESULT AND DISCUSSION

(Optical Microscopy)

• The characteristic feature of observed

coatings is strong refinement of their

microstructure.

• The roughness of substrate contributes

to better adhesion of deposite coatings

and is necessary in the thermal coating

technologies.

• In some place the silicon particles

appeared in the contact places

between the substrate and coatings.

RESULT AND DISCUSSION (Transmission Electron Microscopy)

• The dimension of the molecules differs

and is smaller in HVOF coatings (Figs.

8,11) in comparison to the Plasma Spray

Coatings (Fig. 12).

• (Figs 10,13) containing addition of the

NiCrSiB phase column microstructure.

Molecule fig. 10 is smaller than fig. 13.

the molecule are distributed along the

direction of column progress (fig. 10).

• (Fig. 9,11) below 20 nm, (fig. 8) 50

nm. (Fig. 12) microvoid, (fig. 14)

changeabley direction column

microstructure

RESULT AND DISCUSSION

(Microhardness)

• Highest level: WC-Co-Cr coating; Lowest level: Cr3C2-NiCr coating.

• Differ chemical composition differ microhardness.

• The influence of molecules size on the microhardness level is no crucial.

RESULT AND DISCUSSION

(Wear Erosion Test)

• Fig. 16 show deep furrow. Figures

17-23 the defects characterize dark

contrast.

• The best coating no. 2, 4, 7. blade

no. 4 shows the least failure.

• The deposit coatings have nano

microstructure. And the refinement of

microstructure coatings to the

nanometric dimensions determinately

influence on the wear resistance.

• The wear resistance strongly depends

on the smothness of the coating

surface, which become better if the

size of grains/molecule become lesser.

CONCLUSION

THANK YOU