Method for depositing a coating by dli-mocvd with direct recycling of the precursor compound

Abstract

Process for the chemical vapor deposition by DLI-MOCVD on a substrate of a protective coating composed of at least one protective layer comprising a transition metal M: a) having available, in a feed tank, a mother solution containing a hydrocarbon solvent devoid of oxygen atom and a precursor of bis(arene) type containing the transition metal M to be deposited, and, if appropriate, a carbon-incorporation inhibitor; b) vaporizing said mother solution and introducing it into a CVD reactor in order to carry out the deposition of the protective layer on said substrate; c) collecting, at the outlet of the reactor, a fraction of the gaseous effluent comprising the unconsumed precursor, the aromatic byproducts of the precursor and the solvent, these entities together forming a daughter solution, and; d) pouring the daughter solution thus obtained into the feed tank in order to obtain a new mother solution capable of being used in step a).

1 . Process for the deposition on a substrate of a protective coating composed of one or more layers, at least one being a protective layer comprising a transition metal M in the form of at least one protective material chosen from a carbide, an alloy or a metal, the deposition process being a process for the chemical vapor deposition of an organometallic compound by direct liquid injection (DLI-MOCVD) which comprises the following steps:
 a) having available, in a feed tank, a mother solution containing:   a hydrocarbon solvent devoid of oxygen atom,   said organometallic compound composed of a precursor of bis(arene) type having a decomposition temperature of between 300° C. and 600° C. and comprising the transition metal M, and   if appropriate, a carbon-incorporation inhibitor;   b) vaporizing said mother solution in an evaporator and then introducing it into a chemical vapor deposition reactor in which said substrate to be covered is found; in order to carry out, in the chamber of the reactor, the atmosphere of which is at a deposition temperature of between 300° C. and 600° C. under reduced deposition pressure, the deposition of the protective layer on said substrate;   c) collecting, at the outlet of the reactor, a fraction of the gaseous effluent comprising the unconsumed precursor, the aromatic byproducts of the precursor and the solvent, these entities together forming, under standard conditions, a daughter solution, and;   d) pouring the daughter solution thus obtained into the feed tank in order to obtain a new mother solution capable of being used in step a).   
     
     
         2 . Process according to  claim 1 , wherein step b) of vaporizing and deposition and step c) of collecting said fraction of the effluent are carried out so that the atmosphere of the chamber of the reactor is at a reduced deposition pressure of between 133 Pa and 6666 Pa. 
     
     
         3 . (canceled) 
     
     
         4 . Process according to  claim 1 , wherein the transition metal M is chosen from Cr, Nb, V, W, Mo, Mn or Hf. 
     
     
         5 . Process according to  claim 4 , wherein the transition metal M is at the zero oxidation state. 
     
     
         6 . Process according to  claim 4 , wherein the transition metal M is chromium. 
     
     
         7 . Process according to  claim 4 , wherein the carbide of the transition metal M composing the protective material is of CrC, WC, NbC, MoC, VC or HfC type, or has the stoichiometric Cr 7 C 3 , Cr 3 C 2 , Mo 2 C, Mn 3 C, V 2 C or V 4 C 3 . 
     
     
         8 . Process according to  claim 4 , wherein the alloy of the transition metal M composing the protective material is a base alloy of the transition metal M. 
     
     
         9 . Process according to  claim 4 , wherein the metal composing the protective material is the transition metal M in native form. 
     
     
         10 . (canceled) 
     
     
         11 . Process according to  claim 1 , wherein the precursor of bis(arene) type is devoid of oxygen atom and has the general formula (Ar)(Ar′)M, where M is the transition metal at the zero oxidation state (M 0 ) and Ar and Ar′, which are identical or different, each represent an aromatic group of the type of benzene or benzene substituted by at least one alkyl group. 
     
     
         12 . Process according to  claim 11 , wherein the aromatic groups Ar and Ar′ each represent a benzene radical or a benzene radical substituted by from 1 to 3 identical or different groups chosen from a methyl, ethyl or isopropyl group. 
     
     
         13 . (canceled) 
     
     
         14 . Process according to  claim 1 , wherein the solvent is a monocyclic aromatic hydrocarbon of general formula C x H y  which is liquid under the standard conditions and which has a boiling point of less than 150° C. and a decomposition temperature of greater than 600° C. 
     
     
         15 - 16 . (cancelled) 
     
     
         17 . Process according to  claim 1 , wherein said mother solution further contains, as carbon-incorporation inhibitor, a chlorine-comprising or sulfur-comprising additive, devoid of oxygen atom and with a decomposition temperature of greater than 600° C., in order to obtain the protective material composed of the transition metal M or of the alloy of the transition metal M. 
     
     
         18 . (canceled) 
     
     
         19 . Process according to  claim 1 , wherein, in step c), the collecting of said fraction comprises an operation of selective condensation of the entities present in the effluent at the outlet of the reactor. 
     
     
         20 - 21  (canceled) 
     
     
         22 . Process according to  claim 1 , wherein step c) of collecting said fraction is followed by a step c1) of determination of the concentration of the precursor in the daughter solution obtained, and wherein step d) comprises an operation d0) of adjustment of the concentration of the precursor, as a function of the concentration of the precursor of the daughter solution poured into the feed tank. 
     
     
         23 - 24 . (canceled) 
     
     
         25 . Process according to  claim 1 , wherein steps a) to c) are repeated sequentially N times and the N daughter solutions are saved, and then step d) is carried out by pouring said N daughter solutions into the feed tank in order to obtain a new mother solution capable of being used in step a). 
     
     
         26 . Process according to  claim 1 , wherein the daughter solution obtained in step c) is poured continuously into the feed tank, during the chemical vapor deposition process. 
     
     
         27 . (canceled) 
     
     
         28 . Process according to  claim 1 , wherein the protective coating has a mean thickness of between 1 μm and 50 μm. 
     
     
         29 . (canceled)