摘要:
The method applies to a process such as cementation or chemical vapor infiltration or deposition, the process being carried out in an oven and the method comprising setting operating parameters of the oven, introducing a reagent gas into the oven, the reagent gas containing at least one gaseous hydrocarbon, and extracting from the oven an effluent gas containing reaction by-products of the reagent gas. The effluent gas is subjected to washing in oil that absorbs tars contained in the effluent gas, and information about the progress of the process is obtained by measuring the quantity of tar absorbed by the oil.
摘要:
The method applies to a process such as cementation or chemical vapor infiltration or deposition, the process being carried out in an oven and the method comprising setting operating parameters of the oven, introducing a reagent gas into the oven, the reagent gas containing at least one gaseous hydrocarbon, and extracting from the oven an effluent gas containing reaction by-products of the reagent gas. The effluent gas is subjected to washing in oil that absorbs tars contained in the effluent gas, and information about the progress of the process is obtained by measuring the quantity of tar absorbed by the oil.
摘要:
The substrate (10) is placed in an enclosure (12) and is heated so as to establish a temperature gradient within the substrate such that the substrate has a temperature in its portions remote from its exposed surfaces that is greater than its temperature at said surfaces. A gas constituting a precursor of carbon and comprising at least one saturated or unsaturated hydrocarbon is admitted into the enclosure, with the formation of pyrolytic carbon be favored in the higher temperature portions of the substrate. The gas comprises a mixture containing at least one saturated or unsaturated hydrocarbon and hydrogen, and the substrate is heated in such a manner as to establish a temperature gradient within the substrate on either side of a temperature of 1500 K, with hydrogen having an inhibiting role at temperatures below 1500 K.
摘要:
The substrate (10) is placed in an enclosure (12) and is heated so as to establish therein a temperature gradient such that the substrate has a higher temperature in portions that are remote from its exposed surfaces than at its exposed surfaces. A reaction gas constituting a precursor for the material to be infiltrated is admitted into the enclosure, with formation of the material being enhanced in those portions of the substrate that are at higher temperature. At the beginning of the infiltration process, and at least during the major portion thereof, substrate heating is controlled in such a manner as to maintain the temperature of its exposed surfaces at a value that is no greater than the minimum temperature for the reaction gas to deposit the material that is to be infiltrated, while portions of the substrate that are remote from its exposed surfaces are at a temperature that is greater than the minimum temperature for deposition.
摘要:
A method for densification of porous by CVI in which substrates are loaded into a loading zone of an oven and heated to a temperature at which a desired matrix material is formed from a precursor gas(es). A reative gas containing the precursor gas(es) is admitted into the end of the oven and heated upstream from the loading zone of the substrates. The reactive gas is also preheated prior to entering the oven so that, upon entering the oven, it is brought to an intermediate temperature between ambient temperature and the temperature to which the substrates are heated. In this manner, a very small temperature gradient is obtained throughout the loading zone.
摘要:
Between the start and the end of the chemical vapor infiltration process, filtration conditions are modified by causing at least one of the following infiltration parameters to vary: retention time of the gas, pressure, temperature, concentration of precursor in the gas, and concentration of dopant, if any, in the gas; thereby adapting infiltration conditions to changes in the porometry of the substrate in order to control the microstructure of the material deposited within the substrate, in particular in order to conserve a microstructure that is constant.
摘要:
The invention relates to a heat treatment oven comprising a loading or treatment zone, at least one gas inlet, a gas preheater chamber situated in the oven between the gas inlet and the loading or treatment zone, a susceptor comprising at least a side wall surrounding the preheater chamber and the loading or treatment zone, and a field winding suitable for heating the side wall by induction. The portion of the side wall of the susceptor that is situated around the preheater chamber presents at least two recesses spaced apart circumferentially from one another so as to form portions of reduced thickness in said portion of the side wall.
摘要:
A fiber preform obtained by conforming panels of fiber texture on a former having a surface that reproduces the shape desired for a surface of the nozzle or the nozzle divergent section that is to be made, and by bonding the panels together via their mutually contacting edges, and consolidated fiber reinforcement is formed by shaping the fiber preform impregnated with a consolidation composition comprising a resin, shaping being performed between the former and a jacket applied against the impregnated fiber preform so as to obtain consolidated fiber reinforcement having a fiber volume percentage of at least 35%, and having a thickness of no more than 5 mm over at least a major fraction of its axial dimension. The densification of the fiber reinforcement is continued by chemical vapor infiltration after pyrolyzing the resin so that once densified a part is obtained that has practically the shape and the wall thickness of the nozzle or the nozzle divergent section that is to be made.
摘要:
A fiber preform is obtained by conforming panels of fiber texture on a former having a surface that reproduces the shape desired for a surface of the nozzle or the nozzle divergent section that is to be made. The panels are bonded together via their mutually contacting edges. A consolidated fiber reinforcement is formed by shaping the fiber preform impregnated with a consolidation composition including a resin. The shaping of the fiber preform is performed between the former and a jacket applied against the impregnated fiber preform so as the consolidated fiber reinforcement has a fiber volume percentage of at least 35%, and a thickness of less than 5 mm over at least a major fraction of its axial dimension. The densification of the fiber reinforcement is continued by chemical vapor infiltration after pyrolyzing the resin so that once densified, a part is obtained that has practically the shape and the wall thickness of the nozzle or the nozzle divergent section that is to be made.
摘要:
The invention relates to a heat treatment oven comprising a loading or treatment zone, at least one gas inlet, a gas preheater chamber situated in the oven between the gas inlet and the loading or treatment zone, a susceptor comprising at least a side wall surrounding the preheater chamber and the loading or treatment zone, and a field winding suitable for heating the side wall by induction. The portion of the side wall of the susceptor that is situated around the preheater chamber presents at least two recesses spaced apart circumferentially from one another so as to form portions of reduced thickness in said portion of the side wall.