The term “thermal spray” refers to a family of processes for which solids materials are decomposed into fine particles in a molten or semi-molten condition and accelerated in a gas stream, to form a coating on a substrate. This family can be divided into two categories: the “low speed” processes, less expensive but limited to spray materials with low melting point (metals, enamels), and the “high speed” processes which ensure to produce coatings with high melting point materials such as ceramics (oxides and carbides).

Thermal spraying services tailored to your needs

Thanks to its industrial tools, CITRA proposes a wide range of services. With its 2 booths, it is able to offer 4 thermal spraying processes (see below), each equipped with a set of robotic arm/turntable and its own powder feeder. These thermal spray processes can be tailored to each case for the development of new processes, products or coatings for any applications, to treat surfaces of about 1000x2000mm.

Service offer

As part of its activities, CITRA has been led to develop processes across its entire range of technological resources.

Projection flamme hypersonique (HVOF)

Hypersonic flame projection

Mainly used to perform carbide (WC/Co, Cr3C2), metallic (Ni, Co) and alloys (Inconel, MCrAlY) coatings. The high particle velocity and the significant material flow (up to 9 kg/h) allow to quickly build coatings with high added value technical characteristics. There are many applications such as anti-corrosion and anti-wear protections with the possibility of making thick coatings.

General technical characteristics

Heat sources Oxygen/ kerosene
Flamme’s Temperatue (°C) 3 000
Particles’s velocity (m/s) 700
Porosity rate (%) 0,3 à 2
Adhesion strenght (MPa) 50 – 80
Roughness 3 < Ra< 10
Thickness (mm) 0,1 à 10
Application examples Metal deposits (copper, stainless steel, etc.) and cermets (tungsten carbide with cobalt and / or chromium) DIAMALLOY, METCO, WOKA
Projection plasma atmosphérique (APS)

Atmospheric plasma projection

This technique has a high competitive heat / velocity  balance which allows the production of coatings at interesting deposition rates (from 1 to 5 kg/h). Application areas are large (wear, corrosion, oxidation, thermal barrier, friction) and deposited materials are varied (metals, alloys, ceramics, carbides, cermets).

General technical characteristics

Heat source Plasma Ar + H2, Plasma Ar + He
Flamme temperature (°C) 12 000
Particle speed (m/s) 250
Porosity rate (%) 1 à 10
Adhesion strenght (MPa) 30 – 70
Roughness 5 < Ra< 10
Thickness (mm) 0,1 à 5
Applications examples Ceramic (alumina, zirconia, etc.) and metallic (stainless steel, copper, nickel, various alloys) deposits. METCO 41C, MEDIPURE
Projection par arc-fil

Wire Arc

Generally used for applications requiring large amounts of deposited material (5 to 30 kg/h) to restore damaged components for example. Commonly used materials are zinc, aluminum, copper, molybdenum and steel alloys. With cored wires, carbide or polymer coatings can be envisaged at lower costs than in plasma, especially on temperature-sensitive substrates.

General technical characteristics

Heat source Arc-électrique
Flame temperature (°C) 6 000
Particles velocity (m/s) 150
Porosity rate (%) 8 à 15
Adhesion strenght (MPa) 40
Roughness Ra > 10
Thickness (mm) 0,2 à 10
Application examples Metal deposits (brass, stainless steel, copper, zinc, aluminum, etc.)TAFA
Projection flamme-poudre

Flame-powder projection

First thermal spray process developed in the early twentieth century for anti-corrosion coatings, its implementation is quite simple and inexpensive. The most used materials are self-melting alloys but the spraying of steels, polymers or ceramics is also possible. The SURFACILIM program and the KERAVIVA range products have notably been developed with IMERYS.

General technical characteristics

Heat source Oxygene/ acetylene
Flame temperature (°C) 3 000
Particle velocity (m/s) 40
Porosity rate (%) 10 à 20
Adhesion strenght (MPa) 20 – 40
Roughness Ra > 10
Thickness (mm) 0,2 à 0,5
Application examples Ceramic deposits (alumina, enamels)IMERYS, SAINT GOBAIN)

Cold Spray

Cold spray is a process designed for coating but also for repairing components used in advanced industrial sectors, up to creating 3D shapes. Cold spray belongs to the family of thermal spray methods, but differs from other techniques in that it is a solid-state process. It has many advantages : high thickness, very low porosity, very low oxidation and excellent adhesion.