Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C3/00—Selection of compositions for coating the surfaces of moulds, cores, or patterns
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/006—Continuous casting of metals, i.e. casting in indefinite lengths of tubes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
  • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
  • B22D11/059—Mould materials or platings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
  • B22D13/00—Centrifugal casting; Casting by using centrifugal force
  • B22D13/10—Accessories for centrifugal casting apparatus, e.g. moulds, linings therefor, means for feeding molten metal, cleansing moulds, removing castings
  • B22D13/101—Moulds
  • B22D13/102—Linings for moulds
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C37/00—Cast-iron alloys

Definitions

• the invention relates to a product in the form of powder, for the protection of casting molds cast iron pipes manufactured by centrifugal casting; the casting molds used are commonly referred to as "shells".
• the coatings used for the protection of centrifugal casting shells of cast iron pipes can consist of inoculants and powdered refractory materials, as well as mixtures of silica and bentonite, put in place by projection of an aqueous suspension.
• Such coatings are described, for example, in US Patent 4,058,155 to "Pont-A-
• dry-spray dry powders sprayed onto the shell before pouring the cast iron, powders then referred to as "dry-spray". Whatever the technique used for their deposit, these products are used for several purposes, including:
• the inoculating power of the "dry-spray" can therefore be positioned within fairly wide limits; however, the other effects requested on the product are subject to more constant requirements.
• dry-spray The products used as "dry-spray" are therefore generally composed of a mixture of several components including:
• An inoculant of greater or lesser effectiveness which can typically constitute 30 to 100% of the product; can be used for this purpose, for example, ferro-silicon type alloys containing 0.1 to 4% aluminum and calcium, and possibly other elements that may provide the cast iron with an additional or complementary metallurgical effect .
• Powders of elements or alloys that specifically confer an anti-pitting effect they may be typically the elements or alloys of reducing elements of column 2 of the Mendeleev classification.
• An inert mineral filler for example silica, which can constitute up to 70% of the product.
• Patent FR 2612097 of "Foseco" describes the use, as treatment agent, of Fe-Si-Mg-type alloys whose particles are electrically charged by friction.
• a distribution system which generally comprises:
• the subject of the invention is a powder product, for the protection of molds for centrifugally casting cast iron pipes by dry spraying said product onto the inner surface of said mold, comprising an alloy or a mixture of metal alloys (s) inoculating (S) optionally powders of reducing elements or alloys with an anti-pitting effect, optionally an inert mineral filler, characterized in that it further comprises at least one adjuvant intended to improve the flowability characteristics of said product.
• the flowability is such that the flow time of 50 g of product through the hole of diameter 4 mm of a funnel whose walls form an angle at the top of 60 degrees, is between 17 and 27 seconds for a particle size having a loop at 300 ⁇ m between 99 and 100% and a loop at 63 microns between 10 and 35%.
• the flow time with respect to the same product without said adjuvant is reduced by 5 to 10 s if said same product without said adjuvant flows through the hole of diameter 4 mm, and is between 20 and 27 s if said same product without said adjuvant does not flow through said hole.
• the adjuvant is silicone oil; according to another mode, it is potassium siliconate, and according to yet another mode, microsilica of density less than 0.1.
• the mass proportion of adjuvant in said product is between 0.02 and 0.2%.
• the flowability of the powder must correspond to an optimum between a good distribution capacity, and homogeneity of distribution on the internal footprint of the shell, and the need that after deposition on said footprint, it no longer flows , in particular before the front of liquid iron when it is poured into said shell.
• the latter also has a hammered surface, consisting of a succession of cups, one of whose roles is to retain the powder so that it is not driven by the front of liquid iron. If the flowability of the powder is too great, this precaution is insufficient. Moreover, the characteristics of the systems for handling, dosing and dispensing said powder are different from one user to another, which in practice results in the fact that the characteristics of the powder and the equipment are not always optimized for each other.
• a lack of product in certain areas of the shell will result locally in a lack of inoculation with presence of carbides on the surface and thus increased abrasion and wear of the shell.
• the Applicant has therefore sought to improve the flowability of the powder to facilitate operations prior to its deposit and the deposit itself, while avoiding negative effects after deposit in the shell, ie by ensuring a low flowability when the cast iron is poured into said shell.
• adjuvants may be potassium siliconate, but other adjuvants with a similar behavior as to their effect on flowability are also usable, such as, in particular, silicone oil, micro silica with a density typically of less than 0.1 (usual density for the so-called "chemical" micro silica) or a mixture in any proportions of one or more of these products.
• silicone oil micro silica with a density typically of less than 0.1 (usual density for the so-called "chemical" micro silica) or a mixture in any proportions of one or more of these products.
• the following tests were carried out with 0.06% of adjuvant, but the usual proportion in industrial conditions can be between 0.02 and 0.2%.
• the particle size of the powder product according to the invention is less than 580 ⁇ m and preferably 250 ⁇ m. Examples:
• the flowability characteristics of a powder for "inotubes" are determined by various tests including in particular the flow time of a given quantity through a standardized funnel, the measurement of the shear properties under load and in particular according to the known method. under the name “Jenike test”, the flow time under load which consists of measuring the maximum load at which the product can flow through a hole of given diameter, etc ...
• the particle size has a passing at 300 microns between 99 and 100%.
• the flow hierarchy thus obtained is the same if one uses a test of the type of flow under load as mentioned above.
• said adjuvants make it possible to obtain a flow time for the "inotube", whose particle size has a 63 ⁇ m pass from 10 to 35%, between 17 and 27 s.
• CaSi 20% silicon-calcium alloy known as "CaSi", 30.3% Ca, powder of particle size less than 300 microns.
• the measurement of the particle size shows that it has a 63 ⁇ m pass of 23%.
• the flow time is 28 s.
• Example N ° 2 The product described in Example No. 1 was stored in canvas bags known as "big bags” under a shed for 2 months.
• Example 2 The same mixture was prepared as in Example 1 but with the addition of 0.06% of a 40% solution of potassium siliconate in water homogeneously during the mixing operation. The measurement of the particle size shows that it has a 63 ⁇ m pass of 23%.
• the flow time is 21 s.
• Example No. 3 The product described in Example No. 3 was stored in a "big bag” under a shed for 2 months.
• ferro-silicon with 65.5% Si, 1.3% Ca and 0.95% Al, in powder with a particle size of less than 300 ⁇ m.
• the measurement of the particle size shows that it has a loop at 63 ⁇ m of 31%.
• the flow time is 35 s.
• Example 5 The same mixture as in Example 5 was prepared, but with the addition of 0.06% of a 40% solution of potassium siliconate in water homogeneously.
• the measurement of the particle size shows that it has a loop at 63 ⁇ m of 31%.
• the flow time is 25 s. Used in "dry-spray", this product has given satisfactory results: the pipes are virtually free of punctures: the few punctures present are shallow and allow to meet the specifications; the degree of carbides is 8% and a thickness of ferritic cast iron of 35 ⁇ m has been noted on the external surface of the pipe.
• the flow time is reduced by 7 and 10 seconds for the mixtures which, without adjuvant, flow through the hole of diameter 4 mm (Examples 3 and 6 compared respectively to Examples 1 and 5) and is brought to 27 s in the case of a mixture which, without adjuvant, does not flow through said hole (Example 4 compared to Example 2). More generally, it can be remembered that this time is reduced from 5 to 10 s, if the mixture without adjuvant flows through the hole of diameter 4 mm, and is between 20 and 27 s if the mixture without adjuvant does not flow. not through said hole.
• the adjuvant makes it possible to make the flowability characteristics of the product little dependent on its physical or physico-chemical characteristics, which is observed in particular by comparison between the flow times before and after storage of the "inotubes" of the examples. 3 and 4, while products without adjuvant are significantly sensitive (Examples 1 and 2).

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
• Mold Materials And Core Materials (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 2005
  • 2005-03-22 FR FR0502811A patent/FR2883495B1/fr not_active Expired - Fee Related
• 2006
  • 2006-03-21 KR KR1020077021813A patent/KR20070114295A/ko not_active Application Discontinuation
  • 2006-03-21 MY MYPI20061239A patent/MY147531A/en unknown
  • 2006-03-21 WO PCT/FR2006/000609 patent/WO2006100375A1/fr not_active Application Discontinuation
  • 2006-03-21 CN CNA2006800085342A patent/CN101142042A/zh active Pending
  • 2006-03-21 US US11/794,723 patent/US7896961B2/en not_active Expired - Fee Related
  • 2006-03-21 BR BRPI0609204-7A patent/BRPI0609204A2/pt not_active IP Right Cessation
  • 2006-03-21 EP EP06726108A patent/EP1893369A1/de not_active Withdrawn
• 2007
  • 2007-08-15 ZA ZA200706786A patent/ZA200706786B/en unknown

Non-Patent Citations (1)

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