Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
  • C22B21/00—Obtaining aluminium
  • C22B21/06—Obtaining aluminium refining
  • C22B21/066—Treatment of circulating aluminium, e.g. by filtration
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
  • G01N33/20—Metals
  • G01N33/205—Metals in liquid state, e.g. molten metals

Definitions

• the present invention relates to a method and a device for determining the cleanliness of a metal alloy.
• the object of the invention is to make it possible to determine whether, in a metal alloy, the content of impurities and in particular of oxides resulting from the production of the alloy is unacceptable, acceptable or very low in order to determine whether the alloy in question is usable or not. This problem arises, in particular but not exclusively, in the case of aluminum alloys.
• These impurities resulting from the development of the alloy, in particular of aluminum, can consist essentially of oxides.
• salts, carbides, nitrides, borides and sludges can also be found in the form of particles or a kind of skin forming on the alloy.
• spectroscopic emission different types of chemical analysis, for example by gas chromatography.
• volumetric analysis by centrifugation or filtration techniques or even non-destructive techniques, such as the use of ultrasound or techniques based on the use of X-rays.
• An object of the present invention is to provide a method and a device for determining the impurities in a metal alloy which make it possible to carry out this determination quickly in continuity with the development of the alloy.
• the device for determining the cleanliness of a metal alloy is characterized in that it comprises:
• a shell defining a generally flared container with a vertical axis having an open upper end and a lower end defining an orifice of reduced dimensions
• the filter is an extruded ceramic filter. More preferably, this filter has a porosity of the order of 300 CSI (cell per square inch).
• the device for determining the cleanliness of the alloy is mounted on a mobile carriage.
• the shell and an ingot mold used to recover the alloy having passed through the filter and to determine the quantity thereof are pivotally mounted with respect to the chassis of the carriage around horizontal axes.
• the invention also relates to a method for determining the cleanliness of a metal alloy, characterized in that it comprises the following steps:
• a predetermined quantity of the liquid alloy to be tested is introduced into a flared shell initially brought to a second predetermined temperature, said alloy being at a first predetermined temperature, said shell having a bottom provided with an orifice closed by a filter through which the alloy;
• FIG. 1 is a detail view in vertical section showing, on the one hand, the filtering shell and, on the other hand, the alloy recovery mold;
• FIG. 2 is an example of a calibration curve for the purity of the alloy as a function of the quantity of alloy having passed through the filter;
• FIG. 3 shows a preferred embodiment of the device for determining the cleanliness of the alloy mounted on a mobile carriage
• - Figure 4 shows an intermediate step of using the device according to Figure 3;
• FIG. 5 is a diagram illustrating the use of the device of Figure 1.
• the principle of the invention consists in introducing, into a generally flared shell with a vertical axis, a quantity of the alloy to be tested, this alloy being at a predetermined initial temperature.
• the shell is maintained at a predetermined temperature and the alloy flows through a filter, the characteristics of which will be given in more detail later.
• the quantity of alloy having passed through the filter is collected in an ingot mold in order to determine the volume of alloy having passed through the filter before it is clogged by impurities and, of course, different techniques for measuring the amount of alloy having passed through the filter can be considered.
• the device for determining the cleanliness of the alloy essentially consists, in the embodiment considered, of a filtration shell 10 and of an ingot mold 12 for recovering the filtered alloy. More specifically, the shell 10 defines a flared container 14 whose axis XX 'is vertical. The container 14 decreases in section downwards. The lower part of the shell 10 is completed by a plate 16, preferably removable, defining an orifice of calibrated section 18 communicating with the lower part of the flared container 14. Below the orifice 18 is removably attached a filter 20 which is tightly pressed against the underside 16a of the plate 16, for example using a flange 22 and a spring system 24.
• the filter 20 could be fixed by differently on the lower end of the shell 10 provided that the filter 20 closes the entire orifice 18 and that it is fixed in leaktight manner with respect to the shell.
• the shell 10 comprises a temperature regulation system 26 which may for example consist of a heating resistor 28.
• This temperature regulation system 26 serves to maintain the shell at a constant predetermined temperature before the whole operation of determining the cleanliness of the alloy. In fact the shell will have a higher temperature due to the calorific contribution of the alloy.
• the shell is open at the top and therefore there is atmospheric pressure.
• the determination device also comprises an ingot mold 12 disposed below the filter 20, the ingot mold 12 serving to collect the entire fraction of the alloy which has passed through the filter 20 before the clogging thereof by the impurities contained in the alloy.
• the bottom 30 of the mold 12 is level. It thus determines for example a lower volume V4, a first intermediate volume V3, a second intermediate volume V2 and an upper volume VI.
• the stage bottom of the ingot mold makes it possible to visually and easily determine an approximation of the volume and therefore of the weight of the alloy having passed through the filter by looking at which step of the stage bottom is the free surface of the alloy in ingot mold 12.
• the ingot mold could define a different number of volumes and therefore include a different number of steps, this ingot mold thus giving other approximations on the cleanliness of the alloy.
• the filter 20 is an extruded ceramic filter whose pores are substantially perpendicular to the main faces 20a and 20b of the filter. More preferably, this filter has a porosity expressed in CSI of the order of 300.
• the CSI is the number of cells per square inch.
• the flow of the alloy through the filter is done by simple gravity.
• the shell 10 is maintained by the regulation system 28 at a temperature between 450 and 350 ° C and more preferably between 420 and 430 * C.
• the metal when it is introduced into the shell 10 is maintained at a maximum temperature of 790 * and minimum of 750 * in the case of the alloy mentioned above.
• the surface of the cross section of the orifice 18 is equal to 1 cm 2 .
• FIG. 2 gives a calibration curve C which makes it possible to relate the weight P of alloy collected in the ingot mold 12, that is to say the weight of alloy having passed through the filter, as a function of cleanliness of the PA alloy expressed in mm 2 / kg in the case of the A-S7G alloy. Using this curve, it is therefore possible to associate a weight of cleanliness with the weight of alloy having passed through the filter. More precisely, it is possible to determine different cleanliness zones corresponding to criteria associated with the different uses of the alloy. These zones correspond to the volumes defined by the steps of the mold in FIG. 1.
• the method and the device of the invention can be applied to the determination of the cleanliness of other alloys such as copper alloys, cast irons. It will then be necessary to adapt the specific parameters described above to the particular case of the alloy. These parameters are the first and second temperatures as well as the structure and porosity of the filter.
• the shell must be maintained, before the test, at a temperature of between 100 and 500 ° C. depending on the nature of the alloy.
• the initial temperature of the alloy to be tested must be within a range going from Tl + 50'C to Tl + 250 # C, ⁇ being the liquidus temperature of the alloy. Depending on the alloy to be tested, this temperature will be between 650 * and 850 * C.
• the filter With regard to the filter, its nature must be adapted to the temperatures involved. For example, in the case of cast iron, the filter will be made of more refractory material.
• the device comprises a movable carriage 50 on which are mounted one above the other respectively the shell 10 and the ingot mold 12.
• the shell 10 is pivotally mounted around a horizontal axis 52 linked to the chassis 54 of the carriage 50 and a handle 56 allows the shell 10 to pass from its vertical axis position of use to an inverted position allowing the unloading of the alloy residue after the end of the test operation.
• the mold 12 is pivotally mounted about a horizontal axis 58, which allows the mold 12 to be emptied by pivoting when the test has been completely carried out.
• On the carriage 50 is also mounted an electrical power supply 60 which supplies on the one hand the digital display 62 of a thermometric probe 64 making it possible to measure the temperature of the alloy at the moment when it is introduced into the shell 10.
• a temperature control system 66 is provided for regulating the temperature of the shell 10 via the heating collar 28. It is understood that thus the movable carriage 50 includes all the elements necessary for carrying out the test on the cleanliness of the alloy.
• FIG. 4 there is shown an intermediate step of the test operation.
• the shell 10 and the ingot mold 12 are in the position of use, that is to say that their axes are vertical, and a spoon 70 has been represented with the aid of which the desired quantity of liquid alloy has been taken. necessary for the test, this spoon 70 serving to gradually pour the alloy into the flared container 14 of the shell 10.
• the alloy contained in the spoon 70 is measured at temperature using the thermometric probe 64.
• the device can be used with two different dimensions of the filter section defined by the orifice 18.
• the modification of the section is achieved by changing the plate 16 located under the shell 10, each plate having a suitable section orifice.
• the table in FIG. 5 specifies the temperature ranges of the different aluminum alloys for each of the two filter sections which make it possible to carry out cleanliness measurements with suitable sensitivity.
• the small filtering section is 1 cm 2 .
• the large filter section is 2 cm 2 .
• the founder To calibrate the alloy cleanliness determination device, the founder first performs a reference measurement with a bath whose oxidation state does not cause a waste thereof attributable to the presence of too much of oxides. Then, the routine measurements for this same alloy produced at the same temperature make it possible to compare the number of steps filled with the mold with that of the reference measurement.
• the determination device shown in FIG. 3 is particularly advantageous since it is completely autonomous, comprising the ingot mold and the shell as well as all of the temperature control or regulation elements.
• the entire device can be brought near the melting furnace, the holding furnace or the transfer pocket in which the alloy is contained.
• the mold and the shell are pivotally mounted around horizontal axes, it is easy to empty these two containers after the tests have been carried out.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Medicinal Chemistry (AREA)
• Biochemistry (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Materials Engineering (AREA)
• Food Science & Technology (AREA)
• Manufacturing & Machinery (AREA)
• Physics & Mathematics (AREA)
• Analytical Chemistry (AREA)
• Metallurgy (AREA)
• General Health & Medical Sciences (AREA)
• General Physics & Mathematics (AREA)
• Immunology (AREA)
• Pathology (AREA)
• Sampling And Sample Adjustment (AREA)
• Investigating And Analyzing Materials By Characteristic Methods (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Investigating Or Analyzing Materials Using Thermal Means (AREA)

Applications Claiming Priority (3)

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• 1995
  • 1995-01-26 FR FR9500877A patent/FR2730062B1/fr not_active Expired - Fee Related
• 1996
  • 1996-01-25 JP JP8522683A patent/JPH10513258A/ja active Pending
  • 1996-01-25 EP EP96901852A patent/EP0805980A1/fr not_active Withdrawn
  • 1996-01-25 CA CA002210810A patent/CA2210810A1/en not_active Abandoned
  • 1996-01-25 WO PCT/FR1996/000125 patent/WO1996023222A1/fr not_active Application Discontinuation
  • 1996-01-25 US US08/875,565 patent/US5894085A/en not_active Expired - Fee Related
• 1997
  • 1997-07-24 NO NO973433A patent/NO973433L/no unknown

Non-Patent Citations (1)

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