Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
  • B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
  • B23K35/224—Anti-weld compositions; Braze stop-off compositions
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K20/00—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating
  • B23K20/02—Non-electric welding by applying impact or other pressure, with or without the application of heat, e.g. cladding or plating by means of a press ; Diffusion bonding
  • B23K20/023—Thermo-compression bonding
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F17/00—Compounds of rare earth metals
  • C01F17/20—Compounds containing only rare earth metals as the metal element
  • C01F17/206—Compounds containing only rare earth metals as the metal element oxide or hydroxide being the only anion
  • C01F17/224—Oxides or hydroxides of lanthanides
  • C01F17/235—Cerium oxides or hydroxides
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
  • C01F17/00—Compounds of rare earth metals
  • C01F17/30—Compounds containing rare earth metals and at least one element other than a rare earth metal, oxygen or hydrogen, e.g. La4S3Br6
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/60—Compounds characterised by their crystallite size
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2002/00—Crystal-structural characteristics
  • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
  • C01P2002/77—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by unit-cell parameters, atom positions or structure diagrams
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2004/00—Particle morphology
  • C01P2004/60—Particles characterised by their size
  • C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer

Definitions

• the present invention relates to a composition based on yttrium oxide, on a compound based on cerium and on an organic compound and on its use in the field of welding as an anti-diffusion product.
• the welding-diffusion technique is a known technique described in detail for example in EP 1466692. This technique consists in bringing into contact at high temperature under a certain pressure and for a certain time, two plates of a given material. The welding of the two plates then takes place by diffusion of atoms, which represents the advantage of forming a connection structure equivalent to the basic structure of the material.
• an anti-diffusion or "stop-off" composition is used to prevent welding-diffusion in the areas of the faces of the plates located opposite one of the other, which will later be inflated.
• the anti-diffusion composition forming a diffusion barrier is applied in predefined zones on at least one of the opposite faces of the plates of superplastic material (for example titanium) so that, at the end of the welding-diffusion step, the plates are not welded in the areas covered with the anti-diffusion composition which generally comprises a charge of refractory material which inhibits the diffusion of the atoms of the plates to be welded.
• the anti-diffusion composition must have a certain number of characteristics. It must be able to be applied easily and precisely on the plate and therefore have adequate physicochemical properties, in particular an adequate viscosity. It should preferably not contain toxic compound (s) and be stable over time. It must be able to adhere properly to the material and allow a solid and clean weld to be obtained. The technical problem to be solved is therefore to develop such a composition.
• US 6,924,038 B1 describes a composition based on alumina, titanium oxide and silide. Yttrium oxide and cerium oxide are not described.
• WO 2013/178963 describes a method for producing a metal reinforcement of a turbomachine blade.
• EP 1466692 describes a stop-off composition based on yttrium oxide, the average size of which is preferably 50 ⁇ m. There is no reference to a composition like that of the invention.
• EP 0266073 describes a stop-off composition based on yttrium oxide and a polymeric binder.
• composition of the invention comprises in an aqueous medium:
• an organic compound chosen from the group formed by polyvinylpyrrolidone, polyvinyl alcohol, carboxymethylcellulose and hydroxyethylcellulose.
• the composition according to the invention comprises particles of yttrium oxide. These have a D50 less than or equal to 50.0 pm, more particularly less than or equal to 20.0 pm, or even less than or equal to 15.0 pm, or even less than or equal to 10.0 pm.
• the D50 is generally greater than or equal to 0.5 ⁇ m, or even greater than or equal to 1.5 ⁇ m, or even even greater than or equal to 2.0 ⁇ m.
• the D50 can be between 0.5 pm and 50.0 pm, more particularly between between 2.0 mhh and 20.0 miti, or even between 2.0 miti and 15 miti, or even still between 2.0 pm and 10.0 miti.
• At least one layer of the anti-diffusion composition is applied to a surface of a plate according to a predefined pattern and then localized sintering of the anti-diffusion composition is carried out. according to said predefined pattern by heating resulting from the localized application of a laser beam.
• the size of the yttrium oxide particles is adapted to the thickness of the anti-diffusion barrier after application of the laser beam.
• the yttrium oxide particles can moreover have a D90 of less than or equal to 100.0 ⁇ m, more particularly less than or equal to 50.0 ⁇ m, or even less than or equal to 20.0 ⁇ m.
• the size parameters D50 and D90 are obtained by the laser diffraction technique using a volume distribution.
• D50 corresponds to the median diameter as conventionally understood in statistics, determined from a volume distribution of the diameters of the particles. This is therefore the value for which, on the cumulative volume distribution curve, 50% of the particles have a diameter greater than D50 and 50% of the particles have a diameter less than D50.
• D90 corresponds to the diameter such that 90% of the particles have a diameter less than or equal to D90.
• the yttrium oxide has a mass purity greater than or equal to 99.99%, or even greater than or equal to 99.999%.
• the composition according to the invention also comprises particles of a compound based on cerium.
• This compound can be cerium oxide.
• cerium oxide There is commercially available cerium oxide dispersed in water. See for example the 20% dispersion sold by Alfa Aesar https://www.fishersci.co.uk/shop/products/cerium-oxide-20-h2o-colloidal- dispersion-alfa-aesar-3/11399257 (size of around 10 nm).
• the cerium-based compound can also be prepared by the process P consisting in subjecting a colloidal dispersion D which is heated obtained by neutralizing an aqueous solution of cerium nitrate with a basic aqueous solution.
• This method P is described in EP 0208580.
• an aqueous solution of cerium is used which can be a solution of nitrate of Ce lv or an aqueous solution of nitrate cerium-ammoniacal.
• the aqueous solution of Ce lv salt may also include nitrate of Ce IN but it is desirable that the molar proportion of Ce lv be at least 85% (i.e. Ce lv / Cetotai 3 0.85 ).
• the aqueous salt solution of Ce lv preferably contains little or no impurities in the form of covalent anions such as sulphate ions.
• the concentration of the aqueous salt solution of Ce lv is not critical. It can vary between 0.1 and 2 mol / L. For productivity reasons, it may be advantageous to use a concentrated solution of Ce lv salt at a concentration of between 1 and 2 moles per liter.
• the aqueous salt solution of Ce lv generally has some initial acidity.
• the concentration of H + ions is not critical. Advantageously, it is between 0.1 N and 4
• Neutralization is carried out using a basic aqueous solution which may be an aqueous solution of ammonia, soda or potash.
• a basic aqueous solution which may be an aqueous solution of ammonia, soda or potash.
• an aqueous ammonia solution is used.
• This basic aqueous solution may have a concentration of between 0.1 and 11 N, or even between
• the proportion between the basic solution and the cerium nitrate solution is such that there is no precipitation of cerium in a gelatinous form.
• the proportion between the basic solution and the cerium nitrate solution is preferably such that the neutralization rate r is greater than or equal to 0.01 and less than or equal to 3.0.
• r can more particularly be between 1, 2 and 1, 8.
• r is defined by the formula (n3-n2) / ni in which:
• ⁇ m represents the number of moles of Ce lv in the colloidal dispersion D
• ⁇ n2 represents the number of moles OH necessary to neutralize the acidity provided by the aqueous salt solution of Ce lv ;
• ⁇ n3 represents the number of OH moles provided by the basic aqueous solution.
• the neutralization rate reflects the colloidal state of IV cerium:
• the particles of the colloidal dispersion D which is thus obtained after neutralization have an average diameter d50 generally less than 30 nm.
• the colloidal dispersion D is heated to a temperature between 80 ° C and 200 ° C, preferably between 90 ° C and 150 ° C, or even between 90 ° C and 110 ° C.
• the duration of the heating can vary between 2 and 45 hours, preferably between 2 and 24 hours.
• - M represents an alkali metal chosen from Na or K or else a quaternary ammonium radical
• - x is between 0.01 and 0.2;
• M Nh
• the cerium-based particles have a CeÜ2 type crystalline phase.
• This crystalline phase is determined using X-ray diffraction.
• the particles prepared with the method P described above are composed of a poorly crystallized product, more precisely a product whose crystallization rate can vary from 30% to 70%.
• the mesh parameter can vary from 5.42 to 5.44 angstroms.
• the size of the crystallites is generally less than 60 angstroms.
• the cerium-based particles of the composition have a d50 less than or equal to 200 nm, more particularly less than or equal to 100 nm, or even less than or equal to 15 nm, or even less than or equal to 10 nm.
• the d50 is generally greater than or equal to 1 nm.
• the d50 can be between 1 nm and 200 nm, more particularly between 1 nm and 100 nm, or even between 1 nm and 15 nm, or even between 1 nm and 12 nm or between 5 nm and 12 nm.
• the size parameter d50 is obtained by the dynamic light scattering technique (also called DLS for "dynamic light scattering").
• d50 corresponds to the median diameter as conventionally understood in statistics, determined from a volume distribution of the diameters of the particles. This is therefore the value for which, on the cumulative volume distribution curve, 50% of the particles have a diameter greater than d50 and 50% of the particles have a diameter less than d50.
• the organic compound of the composition according to the invention is chosen from the group formed by polyvinylpyrrolidone, polyvinyl alcohol, carboxymethylcellulose and hydroxyethylcellulose. It is more particularly polyvinylpyrrolidone or polyvinyl alcohol.
• polyvinylpyrrolidone denotes a polymer which
• vinyl pyrrolidone form of a copolymer of vinyl pyrrolidone and of at least one other comonomer copolymerizable with vinyl pyrrolidone, such as for example acrylic acid or an alkyl acrylate.
• the weight-average molecular mass (M w ) of the polyvinylpyrrolidone can be between 10,000 g / mol and 50,000 g / mol, more particularly between 10,000 g / mol and 40,000 g / mol, or even between 10,000 g / mol and 30,000 g / mol.
• Polyvinyl alcohol is a polymer made up of the units of formula: -CH2- CHOH-.
• Polyvinyl alcohol is obtained in known manner by alkaline hydrolysis (soda, potash) of polyvinyl acetate. It is referenced by the following CAS number: 9002-89-5. In the case where the hydrolysis is not complete, it is not excluded that the polyvinyl alcohol also comprises residues of units of vinyl acetate. This is the case, for example, of the polyvinyl alcohol used in the examples, which has a hydrolysis rate of 98%. It is therefore possible to use a polyvinyl alcohol for which the hydrolysis rate is generally greater than 90%, or even 95%, or even even 97%.
• the weight-average molecular mass (M w ) of the polyvinyl alcohol can be between 10,000 g / mol and 100,000 g / mol, more particularly between 20,000 g / mol and 80,000 g / mol, even between 20,000 g / mol and 60,000 g / mol or between 30,000 and 50,000 g / mol.
• M w weight-average molecular mass
• M w denotes the weight average molecular mass and is determined by the steric exclusion chromatography (or GPC) technique.
• the measurement conditions are known to those skilled in the art.
• an aqueous mobile phase and a refractometric detector are generally used.
• Polyethylene glycol (PEG) standards are also generally used to obtain the calibration curve.
• PEG polyethylene glycol
• polyvinylpyrrolidone the following conditions may be used, for example: Acclaim SEC-1000 column from the company Thermofischer (4.6 x 300 mm); mobile phase: 10 mM solution of sodium perchlorate; flow rate: 0.35 mL / min; temperature: 30 ° C; detector: refractometer. More details on the determination of M w can be found in the company brochure
• Sheets / D21517 ⁇ .pdf For polyvinyl alcohol, the following conditions may be used: ultrahydrogel column; mobile phase: methanoLeau 1: 1; detector: refractometer.
• the aqueous medium of the composition according to the invention comprises water.
• the aqueous medium can be water or consist of a mixture of water and at least one liquid organic compound miscible with water.
• liquid designates the physical state of the organic compound at 25 ° C and under 1 atmosphere.
• miscible with water means miscible at 25 ° C in any proportion with water.
• the organic compound may for example be an alcohol such as ethanol or propanol or a ketone such as acetone or butanone.
• the aqueous medium can also comprise soluble compounds which come from particles of yttrium oxide or particles of the cerium-based compound.
• the aqueous medium can comprise free nitrate anions originating from the cerium-based compound prepared by method P described above.
• the aqueous medium can also consist of water and at least one organic compound chosen from the group formed by alcohols, ketones, carboxylic acids and esters of carboxylic acids, the organic compound / water mass ratio being between 0 , 1 / 99.9 and 30/70, more particularly between 0.1 / 99.9 and 20/80, or even between 0.1 / 99.9 and 10/90.
• the invention also applies to the case where an aqueous medium consisting of water and several organic compounds chosen from the group formed by alcohols, ketones, carboxylic acids and esters of carboxylic acids is used, the mass ratio of organic compounds / water being between 0.1 / 99.9 and 30/70, more particularly between 0.1 / 99.9 and 20/80, or even between 0.1 / 99.9 and 10/90.
• composition Stopyt 62A which comprises by weight, from 30% to 40% of isopropyl alcohol, from 10% to 50% of methyl isobutyl ketone and less than 10% of 2- phthalate ethylhexyl.
• the phthalate has a recognized toxicity or the composition described in EP 0266073 which comprises butyl cellulose acetal.
• the proportions by weight of the components of the composition can be as follows. These proportions are given by weight relative to the total weight of the composition.
• the proportion by weight of yttrium oxide can be between 25.0% and 50.0%, more particularly between 30.0% and 50.0%, or even more particularly from 35.0% to 45, 0%, or even between 37.0% and 43.0%.
• the proportion by weight of cerium-based particles can be between 1.0% and 10.0%, more particularly between 1.0% and 7.0%, or even more particularly between 1.0% and 5.0 %, or even between 2.0% and 5.0%.
• the proportion by weight of the organic compound may be between 0.1% and 5.0%, more particularly between 0.1% and 2.0%, or even more particularly from 0.1% to 1.0%, or even still between 0.1% and 0.5%. It will be noted that the proportion of the organic compound is low, which makes it possible to avoid the rejection of toxic organic compounds, in particular during diffusion welding.
• composition of the invention essentially consists of a mixture in an aqueous medium:
• an organic compound chosen from the group formed by polyvinylpyrrolidone, polyvinyl alcohol, carboxymethylcellulose and hydroxyethylcellulose.
• composition of the invention consists of a mixture in an aqueous medium:
• an organic compound chosen from the group formed by polyvinylpyrrolidone, polyvinyl alcohol, carboxymethylcellulose and hydroxyethylcellulose.
• composition of the invention generally has a pH greater than 7, more particularly between 8 and 10.
• the composition of the invention does not include zirconium oxide and / or hafnium oxide.
• the composition of the invention can be prepared by the following process.
• An aqueous dispersion of cerium-based particles is mixed together, to which water, and the organic compound, may have been added.
• the yttrium oxide is then added with stirring in the form of a dry powder.
• a shearing agitator is advantageously used, such as for example an agitator of the ultraturrax or Rayneri type.
• the aqueous dispersion of the cerium-based particles prepared by method P generally has a pH of between 0 and 1, or even close to 1. It has been unexpectedly found that, although this dispersion aqueous is rather stable at acidic pH, a composition according to the invention can be obtained having a pH between 8 and 10 which is stable over time (that is to say exhibiting no settling of the particles).
• the composition of the invention may have a viscosity measured at 20 ° C of between 1.0 and 100.0 Pa s, more particularly between 1.0 and 50.0 Pa s when the shear rate is equal to 1 s - 1 .
• the composition of the invention may have a viscosity measured at 20 ° C of between 0.1 and 10.0 Pa s, more particularly between 0.1 and 5.0 Pa s when the shear rate is equal to 10 s - 1 .
• the composition of the invention can thus be in the form of a fluid composition or a paste.
• composition of the invention as described above can be used as an anti-diffusion product.
• the composition as described above can be used to form a diffusion barrier, in particular in a welding-diffusion process.
• This anti-diffusion (or "stop-off") product is used in a welding-diffusion process of two metal parts.
• the method consists in bringing two metal parts into contact, in particular in the form of plates, compressed one against the other and heated to a temperature suitable for causing a diffusion of the metal atoms, the anti-diffusion composition of the invention having been applied to at least one zone of the faces of the parts located opposite one another, so that, at the end of the heating step, the parts are not welded in the zone or zones covered of said composition.
• the parts can be titanium or a titanium-based alloy.
• the temperature to which the rooms are heated is generally at least 700 ° C, or even at least 800 ° C.
• This process is a process for manufacturing a hollow mechanical part by welding-diffusion and superplastic forming, comprising the following steps:
• step b) bringing to the superplastic forming temperature of said mold and injection under the superplastic forming pressure of an inert gas by said passage into said cavity, which causes the swelling of the stack and the superplastic forming allowing obtaining a rough outline of the mechanical part, step b) being carried out by the sequence of the following steps:
• the welding-diffusion technique consists in bringing into contact at high temperature, under a certain pressure and for a certain time, two plates of a given material. The welding of the two plates then takes place by diffusion of atoms, which has the advantage of forming a bonding structure equivalent to the basic structure of the material.
• an anti-diffusion composition or “stop-off” is used to prevent the diffusion welding in the areas of the faces of the plates located opposite one of the other, which will subsequently be inflated to obtain a hollow mechanical part.
• the anti-diffusion composition forming a diffusion barrier is applied in predefined zones on at least one of the opposite faces of the plates of superplastic material (eg titanium) of so that, at the end of the diffusion-welding step, the plates are not welded in the areas covered with the anti-diffusion composition which generally comprises a charge of refractory material which inhibits the diffusion of the atoms of the plates to be welded .
• superplastic material eg titanium
• the assembly of plates selectively welded by diffusion welding is generally then subjected to a superplastic forming by heating the assembly to a temperature compatible with a superplastic behavior of the material of the plates, in a generally closed mold.
• An inert gas is then injected under controlled pressure into the non-welded areas of the assembly, thereby allowing the plates to swell according to the profile of the mold.
• the quality of the weld resulting from the welding-diffusion stage depends on the operating parameters: temperature, pressure and time but also on the parameters linked to the elements to be assembled: metallurgical structure, surface condition (cleanliness, roughness). Consequently, it is essential to eliminate any source of contamination of the surfaces to be assembled before the temperature setting of the welding-diffusion step.
• an anti-diffusion composition composed of a binder, generally organic, and a powder of an anti-diffusion material formed of a filler.
• refractory material such as a ceramic (for example yttrium oxide, alumina or boron nitride or graphite). This anti-diffusion material inhibits the diffusion of atoms from the materials of the plates to be welded.
• the binder After applying the anti-diffusion composition according to a predefined pattern corresponding to the areas of the surfaces not to be joined by welding-diffusion, the binder is generally degraded so as to retain only the powder of the anti-diffusion product, which has anti-diffusion properties. .
• This application of the anti-diffusion composition is generally carried out by the known screen printing technique which has drawbacks which are recalled in EP 1466692.
• the present invention aims to propose an improvement of the process described in EP 1466692 by the use of a new anti-diffusion composition having particular physicochemical and adhesion properties.
• This process is easy to implement because it simplifies the deposition step since it is possible to deposit the anti-diffusion composition directly without the intermediary of a screen printing screen or a layer of masking product.
• sintering makes it possible to achieve good adhesion of the anti-diffusion composition to the (or) face (s) concerned (s) of the (or) primary part (s), which eliminates completely the risks of migration of anti-diffusion particles in the zones which are to be welded by welding-diffusion.
• the step of sintering by laser beam induces a heating which makes it possible to degrade the organic compound of the composition, therefore to eliminate it.
• the principle of sintering a mineral powder by laser beam is presented in application FR 2772021 in the context of a marking application, in particular for decoration.
• step b1) of applying a layer of the anti-diffusion composition is carried out by a method known to those skilled in the art, for example by spraying, coating, serigraphy, etc.
• This arrangement can be implemented in a simple manner by means of spray nozzles which directly project the anti-diffusion composition over the entire surface of said at least one face of the primary parts made up of plates.
• the sintering step b2) is carried out in air or, preferably, under a neutral atmosphere (of inert gas), in particular under an argon atmosphere.
• a neutral atmosphere of inert gas
• step b3) of removal of the unsintered product is carried out by a non-abrasive operation, and this in order not to damage the surfaces to be welded by diffusion welding.
• step b3) of removing the unsintered product is carried out by washing, which constitutes a very simple means.
• This step b3) of removing the unsintered product can also be carried out by any other action, in particular mechanical, non-abrasive, such as brushing.
• the laser is directed by a control system controlled by computer as is already known in the field of laser marking. Likewise, it is advantageously provided that, for each area of the route, said control system starts the route of the corresponding portion of the route inside said area. In this way, the risks of point defects (which may be due to the prolonged application of the laser beam) are eliminated on the edge of the areas covered with the sintered anti-diffusion composition, that is to say at the interface of the welded and non-welded areas.
• the laser beam is adjusted so that it provides sufficient energy to the to effect the sintering of the particles of the anti-diffusion composition, without carrying out the complete fusion of the particles and while creating a diffusion phenomenon between the anti-diffusion composition sintered diffusion and the material on which the composition is deposited.
• the laser beam also makes it possible to remove the water from the anti-diffusion composition and to degrade and eliminate the organic compound present in said composition.
• the laser After the laser has passed, it is possible to remove the anti-diffusion composition by any suitable mechanical process (wiping, brushing, etc.) or even by immersion in a liquid subjected to a flow of ultrasound.
• the present invention also relates to a manufacturing method as defined above, characterized in that said mechanical part is a hollow blade of a turbomachine, in particular a fan rotor blade, and in that in step a) are supplied three primary parts consisting of a primary upper surface, a central plate and a primary lower surface.
• the three primary parts are made of plates.
• the subsequent steps of the process (after step b3)) are known and are the following:
• the stack is welded by diffusion welding in an isostatic compression enclosure so as to ensure an intimate connection between the primary parts constituting the blade, except at the location of the above passage and areas covered with the layer of sintered anti-diffusion composition;
• the primary parts constituting the blade are formed under superplastic conditions by applying an inflation pressure in the internal cavity so as to obtain the desired profile.
• This process is applicable to the production of other hollow mechanical parts, in particular wings, boxes, hoods, beams or any other hollow mechanical part, possibly structural.
• the aqueous dispersion of the cerium-based compound (denoted DA1) used for the preparation of the compositions of the examples was prepared by a neutralization / heating process, according to the teaching of EP 0208580, in particular that of the examples of this patent application, more particularly that of Example 1 (heating to 100 ° C.).
• the polyvinyl alcohol used is sold by Sigma-Aldrich and has a molecular weight by weight M w of less than 30,000 g / mol.
• the polyvinylpyrrolidone used is a vinylpyrrolidone homopolymer sold by Sigma-Aldrich and has a molecular weight by weight M w of the order of 40,000 g / mol.
• Viscosity measurement a Kinexus Malvern plan rheometer was used. The viscosity measurements were made at 20 ° C. For each measurement, the sample is shaken briefly by shaking the bottle. 15 drops are deposited, equivalent to about 0.9 g of product, and wait for the air bubbles to disappear before starting the measurement.
• Membership measures were done as follows. Using an automatic film applicator, a film of the composition to be tested is formed on a metal plate of thickness 100 ⁇ m. The plates are then steamed 10 min at 120 ° C. Next, commercial tape is applied to the film in order to stick it uniformly on it. Press twice with your fingers to make it adhere, then tear off the adhesive tape.
• the uplift rate is then calculated as follows:
• Example 2 for the compositions based on polyvinyl alcohol, a procedure similar to that described in Example 1 was used. The DA1 / polyvinyl alcohol mixture was heated under agitation at 50 ° C. for 90 minutes before adding yttrium oxide.
• compositions of Table I are prepared according to a procedure identical to those described in Examples 1 or 2. Board
• aqueous medium water; % given by weight relative to the composition as a whole polyvinyl alcohol hydrolyzed to 98% of M w 13000-23000 g / mol from Sigma-Aldrich (ref. 348406)
• compositions of Examples 1 to 7 have a better pullout rate.
• organic compounds PVP and polyvinyl alcohol are the most interesting because the pullout rate can be less than 10%.
• compositions were also prepared with yttrium oxide particles having another D50.
• D50 1 miti
• the composition is very viscous.
• D50 3 miti
• the composition has a lower viscosity.
• D50 is preferably greater than or equal to 1.5 ⁇ m, or even greater than or equal to 2.0 ⁇ m.

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• Chemical & Material Sciences (AREA)
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• Life Sciences & Earth Sciences (AREA)
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• Inorganic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Pressure Welding/Diffusion-Bonding (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

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• 2019
  • 2019-10-29 WO PCT/EP2019/079488 patent/WO2020089207A1/fr unknown
  • 2019-10-29 CN CN201980072741.1A patent/CN112969665A/zh active Pending
  • 2019-10-29 KR KR1020217016115A patent/KR20210084570A/ko unknown
  • 2019-10-29 JP JP2021523676A patent/JP2022506353A/ja active Pending
  • 2019-10-29 EP EP19794565.2A patent/EP3873851A1/de active Pending
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