METAL SPRAYING / METAL SPRAYING / METALLIZING / FLAME METALLIZING / FLAME SPRAYINGSPRAYINGTHERMAL SPRAYTHERMAL SPRAYINGING

1

Definitions Metallizing or Metal Spraying is the

process of applying molten metal to a base metal surface in the form of a fine spray that bonds to the base metal and forms a metal coating.

Flame Spraying defines the deposition of materials, both metallic and non-metallic, by the use of a combustion flame.

Thermal Spraying is a process that deposits finely divided particles of metals, intermetallics, metallic oxides or plastics in the molten or semi molten condition to form an adherent coating on a suitable substrate.

2

Surface properties of Surface properties of material/partmaterial/part

Wear− mechanical;− corrosive-mechanical.

Criteria: wear resistance (by mass/volume, relative)

Methods of surface reinforcement− peening;− surface alloying and hardening;− coatings (sprayed coatings, vapor deposited

coatings, cladded coatings, galvanic coatings, diffusion coatings);

− metal cladding (bimetal materials).

3

Coatigns’ processesCoatigns’ processes

CHEMICAL ELECTROCHEMICAL THERMOCHEMICAL THERMOCOATING VAPOR DEPOSITION MECHANICAL

4

Comparison of the coating Comparison of the coating processesprocesses

5

Thermal spray Thermal spray methodsmethods

CHEMICAL ELECTROCHEMICAL THERMOCOATING VAPOR DEPOSITION MECHANICAL

6

cold gas spraying

(CGS)

laser spraying

(LS)

molten-metal

flame spraying

Thermal spraying

Sprayed coating’s structureSprayed coating’s structure

Typical structure of a coating

7

Sprayed coatings’ Sprayed coatings’ materialsmaterials

8

Surface Preparation(i) Rough threading, (ii) Grit blasting, (iii) Electric bonding, (iv) Studding, (v) Sanding or grinding,(vi) Rough machining or grooving, (vii) Spray bonding (molybdenum

and exothermically reactive materials)

9

Flame spraying Flame spraying

10

- flame temperature:• acetylene/oxygen 3160 ºC;• propane/oxygen 2850 ºC;• hydrogen/oxygen 2660 ºC.

- sprayed materials:• wire: metals and metal alloys;• powder: pure metals, alloys, oxides, cermets,

composite powders.

WIRE SPRAYING

POWDER SPRAYING

Arc sprayingArc spraying

11

• temperature inside the arc: 6500 ºC;• voltage 18 – 40 V, current 50 – 150 A;• sprayed materials: electroconductive alloys, ceramics can be deposited, when using core wires.

Plasma sprayingPlasma spraying

12

• plasma temperature: up to 30000 ºC.• virtually all existing materials.

Plasma transfered arc Plasma transfered arc spraying (PTA)spraying (PTA)

13

• Fe, Ni, Co, Cr based alloys, stainless steels, cermets

Laser claddingLaser cladding

14

• virtually all metal alloys, cermets and ceramics.

Detonation gun Detonation gun sprayingspraying

15

• flame temperature: 4000 ºC.

High-velocity oxy fuel spraying High-velocity oxy fuel spraying (HVOF)(HVOF)

16

• gas temperature: 3000 ºC;• sprayed materials: virtually all existing

materials, in practice mostly carbide/metal

and carbide / self-fluxing alloy mixtures.

Cold sprayingCold spraying

17

• gas temperature: under the

phase transition temperature;• sprayed materials: pure Al, Zn, Cu, Ni

and babbites.

Thermal energy vs. kinetic energy Thermal energy vs. kinetic energy in thermal sprayin thermal spray

18

The

rmal

Ene

rgy

Kinetic Energy

WARCS

PS

FS

HVOF

CS

Wirearc Spray

Plasma Spray

Flame Spray

High velocity oxy fuel

Cold Spray

Melt or partially melt

Solid

Applications of Sprayed Coatings

Sprayed coatings are applied, to: Obtain corrosion resistance by spraying Zn and Al. Build up worn out surfaces of machine components

e.g. motor armature shafts. Mechanically size a component that has not been

produced to correct specifications. Hard face a component to achieve desired

hardness, wear resistance, etc. Provide thin coatings of noble metals to small

areas where conventional plating would not be economic.

Obtain reflecting surfaces (e.g. AI is sprayed on the back of glass).

Obtain conductive surface on a poor conductor (e.g. Cu or Ag is sprayed on glass or plastics).

Provide decorative effects on architectural works.

19

Applications (1)Applications (1)

wear resistant coatings (pumps, compressors, camshafts, etc.) – except for cold spraying;

corrosion resistant coatings (pipelines, building constructions, etc.);

20

Applications (2)Applications (2)

temperature resistant and dielectrical coatings (gas turbines, flue tubes);

antifriction coatings (sliding bearings);

size restoration (shafts, bearings, etc.)

21

Applications (3).Applications (3).HVOF sprayed pot rolls for continuous galvanizing line HVOF sprayed pot rolls for continuous galvanizing line

for steel strips.for steel strips.

22

Applications (4)Applications (4)Sprayed coatings in an aircraft engineSprayed coatings in an aircraft engine

23

Applications (5)Applications (5)Process automation. Flame spraying by Kuka robot.Process automation. Flame spraying by Kuka robot.

24

Advantages of Sprayed CoatingsPorosity and oil retention capacity of the sprayed

metal is a major advantage of sprayed coatings.

A metal of the right characteristics can be surfaced at a particular point only where needed.

During spraying, the parts are kept cool there by avoiding the danger from warpage.

For corrosion resistance purposes, Zn and Al can be applied to any practical desired thickness.

25

Disadvantages of sprayed coatings

All sprayed metal is brittle and therefore is limited to use on machine elements where it is not necessary for the coating to add strength.

26

THANK YOUTHANK YOU

27