120
Remanufacturing and Advanced Machining
and computer control of the spraying process to obtain coating of the desired
characteristics.
2.6 PROCESSES OF HARD ALLOYS COATINGS
Hard coatings with a thickness of a few microns are widely applied to improve performance of tools, for example, in cutting, forming and casting applications, and
components, for example, in automotive and aerospace applications (Mitterer, 2014).
Different methods have been developed to fabricate hard coatings, including thermally activated chemical vapor deposition (CVD), plasma-assisted physical vapor
deposition (PVD), plasma-assisted chemical vapor deposition (PACVD), and laserassisted methods such as pulsed laser deposition. The coatings synthesized with
these methods offer high hardness, oxidation and wear resistance, thermal stability,
diffusion barrier properties, and in some cases also low friction and even smart, selfadaptive properties (Mitterer, 2014).
Chemical vapor deposition (CVD) is a well-known chemical method where a film
is deposited on the substrate surface through chemical reaction from a gas-phase
or vapor-phase precursor through application of activation energy (Madhuri, 2020).
Several gases, distinguished as a source gas and a carrier gas, are admitted into the
vacuum chamber, and after dissociation between the species, the newly formed molecules are deposited on the heated substrate as shown in Figure 2.8.
Madhuri (2020) lists various modifications of CVD, such as atmospheric pressure CVD, low-pressure CVD, where the pressure is below ambient (0.6–1.33 mbar),
laser CVD where laser is used to enhance chemical reaction, plasma-enhanced CVD
where plasma enhances the decomposition process, photochemical vapor deposition,
chemical vapor infiltration, and chemical beam epitaxy. The operating parameters,
modes, and conditions can be selected based on properties of a substrate material
and designed application. Mechanical and thermal properties and phase stability
such as melting point and thermal conductivity of a coating material should be considered when choosing appropriate process parameters (Madhuri, 2020)
FIGURE 2.8 Schematic diagram of a plasma CVD (chemical vapor deposition) system
( Public domain).
Remanufacturing and Advanced Machining
and computer control of the spraying process to obtain coating of the desired
characteristics.
2.6 PROCESSES OF HARD ALLOYS COATINGS
Hard coatings with a thickness of a few microns are widely applied to improve performance of tools, for example, in cutting, forming and casting applications, and
components, for example, in automotive and aerospace applications (Mitterer, 2014).
Different methods have been developed to fabricate hard coatings, including thermally activated chemical vapor deposition (CVD), plasma-assisted physical vapor
deposition (PVD), plasma-assisted chemical vapor deposition (PACVD), and laserassisted methods such as pulsed laser deposition. The coatings synthesized with
these methods offer high hardness, oxidation and wear resistance, thermal stability,
diffusion barrier properties, and in some cases also low friction and even smart, selfadaptive properties (Mitterer, 2014).
Chemical vapor deposition (CVD) is a well-known chemical method where a film
is deposited on the substrate surface through chemical reaction from a gas-phase
or vapor-phase precursor through application of activation energy (Madhuri, 2020).
Several gases, distinguished as a source gas and a carrier gas, are admitted into the
vacuum chamber, and after dissociation between the species, the newly formed molecules are deposited on the heated substrate as shown in Figure 2.8.
Madhuri (2020) lists various modifications of CVD, such as atmospheric pressure CVD, low-pressure CVD, where the pressure is below ambient (0.6–1.33 mbar),
laser CVD where laser is used to enhance chemical reaction, plasma-enhanced CVD
where plasma enhances the decomposition process, photochemical vapor deposition,
chemical vapor infiltration, and chemical beam epitaxy. The operating parameters,
modes, and conditions can be selected based on properties of a substrate material
and designed application. Mechanical and thermal properties and phase stability
such as melting point and thermal conductivity of a coating material should be considered when choosing appropriate process parameters (Madhuri, 2020)
FIGURE 2.8 Schematic diagram of a plasma CVD (chemical vapor deposition) system
( Public domain).