The term “thermal spraying” refers to a family of processes by which solids materials are decomposed into fine particles in the liquid or plastic state in a gas stream, to form a coating by stacking on a substrate. This family can itself be divided into two categories: the “low speed” processes, less expensive but limited to the projection of materials with low melting point (metals, enamels), and the “high speed” processes which make it possible to produce dense coatings of materials with a high fusion point such as ceramics (oxides and carbides).

Thermal spraying services tailored to your needs

With its industrial tools, CITRA has a varied offer in its thermal projection activity. With its 2 projection booths, it is able to offer 4 thermal projection processes (see below), each equipped with a robotic arm assembly / automated turntable and its own powder dispenser. These projection systems are able to be adapted case by case to the development needs of new processes, products or coatings on applications of any type, 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 resources.

Projection flamme hypersonique (HVOF)

Hypersonic flame projection

Technique used to make coatings of carbide type (WC / Co, Cr3C2) and alloys (Ni, Co, Inconel …). Deposits made at high hourly rates (up to 9 kg / h) and of excellent quality make this process widely used in aeronautics (WC-12Co abrasion resistant coating).


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 type of process has a high performance heat / speed compromise which allows the realization of coatings at interesting deposition rates (from 1 to 5 kg / h). The fields of application are vast (wear, corrosion, oxidation, thermal barriers, friction) and the various deposited materials (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

Arc-fil projection

Generally used for applications requiring large amounts of deposited material (5 to 30kg / h) or for applications such as reloading worn parts. 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, in particular 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 spraying process developed in the early twentieth century for the realization of anti-corrosion zinc coatings, it is simple to implement and inexpensive. The most used materials are the self-melting alloys but the projection of steels, polymers or certain ceramics is possible. The SURFACILIM program and the products of the KERAVIVA range with IMERYS have notably been developed.


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 solid state process mainly aimed at coating achievment and repair of components employed inadvanced industry sectors.


Cold Spray ‘s advantages

This thermal spray process is based on the acceleration of solid powder particles by a supersonic jet of gas.

The significant advantages of Cold Spray, compared to others thermal sray processes are :

  • High thickness (several mm)
  • Dense coatings
  • No porosity
  • No oxydation
  • High mechanical properties (adhesion)
  • High deposition efficiency