A method for assembling a first part and a second part by brazing, comprising the following steps: i) preparing a first part made of carbon, titanium-based, nickel-based or made of a CoCr alloy, ii) preparing a second part made of carbon, titanium-based, nickel-based or made of a CoCr alloy, iii) bringing a filler material into contact with the first part and with the second part, iv) heating the assembly obtained at the step iii), v) cooling the assembly so as to form a solder joint between the part made of carbon and the metal part, whereby the parts are assembled, characterised in that the preparation or the first part during step i) and optionally the preparation or the second part during step ii) is performed according to the following sub-steps a) to d): a) providing the first part made of carbon, titanium-based, nickel-based or made of a CoCr alloy, b) carrying out a plasma treatment with a neutral gas, on the first part whereby the part is cleaned and an active surface is formed on the part, c) depositing a first layer comprising an active element over the active surface of the first part, the active element being a carbide-forming element, and d) depositing a second layer made of gold over the first layer, whereby the first layer is protected from oxidation and good wetting is ensured and in that the heating at step iv) is performed up to an assembly temperature higher than the melting temperature of the filler material, so as to melt the filler material, and maintaining the assembly temperature for a hold time period, the assembly temperature being lower than 450°C. i) preparing a first part made of carbon, titanium-based, nickel-based or made of a CoCr alloy, ii) preparing a second part made of carbon, titanium-based, nickel-based or made of a CoCr alloy, iii) bringing a filler material into contact with the first part and with the second part, iv) heating the assembly obtained at the step iii), v) cooling the assembly so as to form a solder joint between the part made of carbon and the metal part, whereby the parts are assembled, characterised in that the preparation or the first part during step i) and optionally the preparation or the second part during step ii) is performed according to the following sub-steps a) to d): a) providing the first part made of carbon, titanium-based, nickel-based or made of a CoCr alloy, b) carrying out a plasma treatment with a neutral gas, on the first part whereby the part is cleaned and an active surface is formed on the part, c) depositing a first layer comprising an active element over the active surface of the first part, the active element being a carbide-forming element, and d) depositing a second layer made of gold over the first layer, whereby the first layer is protected from oxidation and good wetting is ensured and a) providing the first part made of carbon, titanium-based, nickel-based or made of a CoCr alloy, b) carrying out a plasma treatment with a neutral gas, on the first part whereby the part is cleaned and an active surface is formed on the part, c) depositing a first layer comprising an active element over the active surface of the first part, the active element being a carbide-forming element, and d) depositing a second layer made of gold over the first layer, whereby the first layer is protected from oxidation and good wetting is ensured and in that the heating at step iv) is performed up to an assembly temperature higher than the melting temperature of the filler material, so as to melt the filler material, and maintaining the assembly temperature for a hold time period, the assembly temperature being lower than 450°C.