Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
  • B22C1/02—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by additives for special purposes, e.g. indicators, breakdown additives
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C1/00—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds
  • B22C1/16—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents
  • B22C1/18—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents
  • B22C1/186—Compositions of refractory mould or core materials; Grain structures thereof; Chemical or physical features in the formation or manufacture of moulds characterised by the use of binding agents; Mixtures of binding agents of inorganic agents contaming ammonium or metal silicates, silica sols
  • B22C1/188—Alkali metal silicates
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C9/00—Moulds or cores; Moulding processes
  • B22C9/02—Sand moulds or like moulds for shaped castings

Definitions

• the object of the invention relates to a moulding or core sandmix with an inorganic binder, which is used for making castings of all types of alloys.
• the moulding and core sandmixes prepared with use of inorganic binders are used in founding engineering for many years. Their main advantage is low emission of harmful gases during pouring with liquid metal compared to moulding sandmixes with organic binders.
• the main disadvantage is poor knock-out properties, which makes them unsuitable for making complex castings with varying thicknesses of walls. In addition to poor knock-out properties these sandmixes are considered to be difficult to regenerate mechanically.
• the moulding sandmix with inorganic binder consists of: granular matrix, which is usually formed by generally available quartz sand, binder and hardener.
• the hardening process of cores is carried out with use of gaseous carbon dioxide, influence of increased temperature or electromagnetic radiation from the microwave temperature range.
• the liquid organic hardeners are usually used, consisting of glycerol esters and ethylene glycol, mainly glycerol mono-, di- and triacetates and ethylene glycol diacetates.
• floster technology the method of preparing sandmixes with use of liquid esters
• the hardener is called flodur.
• the easy to knock-out moulding or core sandmix is known from the Polish patent description no. 106 510 , which consists of quartz sand and water glass, where the calcium carbonate in the amount of 0.5 to 25% of sand weight is used to facilitate the knock-out of sandmix.
• the moulding or core sandmix based on quartz sand is also known from the Polish patent description no. 128 721 , which contains coal dust or other bright coal carrier in the amount of 0.5 to 8 parts by weight, preferably in the amount of 2.0 to 6.0 and bauxite dust in the amount of 0.5 to 8.0 parts, preferably 2.0 to 4.0 parts and the water glass in the amount of 2.0 to 10.0 per 100 parts by weight of sand.
• the moulding or core sandmix with water glass and inorganic loosener is known from the patent description PL 166 929 B1 , which contains calcium phosphate in the amount of 50-150% by weight compared to amount of the binder, which is used as an agent improving the knock-out properties.
• the moulding or core sandmix is also known from the patent description PL 206 691 B1 which contains water glass and mineral porous additive with granular structure as a loosening additive, previously subjected to thermal treatment in temperature of 950 - 1150°C in the amount of 0.1 to 2.0 parts by weight per 100 parts by weight of the matrix.
• This additive consists of by weight: 70 - 80% of silica, 10 - 20% of aluminium oxide, 1 - 3% of ferric oxide, 1 - 8% of calcium and magnesium oxide and 5 - 8% of sodium and potassium oxide.
• the main disadvantage of such additive is the large difference of density compared to granular matrix, which inhibits the mixing process of moulding sandmix components.
• the aim of this invention is to eliminate the disadvantage of state of the art in the scope of technology of sandmixes with inorganic binder, which is poor knock-out property, related to the phenomenon of sandmix strengthening under the influence of heating as a result of a contact with high temperature of casting alloy poured into the casting mould.
• the object of the invention is moulding or core sandmix with inorganic binder, the matrix of which is the fireproof granular material, which contains the inorganic loosening additive and possibly a hardener, which is characterized that as a loosening additive it contains fine-grained vermiculite, a material, which is a magnesium, iron and lithium hydrated aluminosilicate or fine-grained pearlite ore which is a transformed igneous rock in a form of potassium-sodium aluminosiliocate glass.
• the vermiculite is formed by hydrolysis and then weathering of biotite or phlogopite, i.e. potassium-magnesium mica. It is introduced at the sandmix preparation stage, during which the fine-grained fraction of vermiculite is covered with a binder layer and evenly distributed within the entire volume.
• the pearlite ore was formed from volcanic lava, originating from the eruption of undersea volcanoes in ancient geological eras. As a result of rapid cooling and contact with sea water, the lava has closed drops of water inside it.
• the pearlite ore is introduced at the stage of preparation of moulding or core sandmix, during which the pearlite ore grains are distributed evenly among the matrix grains and are covered with a layer of a binder.
• the analogous phenomenon takes place in case of use of the pearlite ore in moulding or core sandmix.
• the small grains of pearlite ore covered with silicate glaze formed in the sandmix increase their volume as a result of transformation of water trapped in the structure of pearlite ore into water steam.
• the rapid increase of pearlite causes destruction of hardened binder, thus lowering the final strength of a sandmix, what contributes to facilitating the castings knock-out process.
• the preferable effect of using the solution according to the invention is that the introduction of fine-grained loosening additive in the form of vermiculite or pearlite ore eliminates the secondary reinforcements of sandmixes with inorganic binders, thus improving the knock-out process.
• the additive is being introduced at the stage of preparation of a sandmix and has no negative influence on sandmixes mixing process and does not cause deterioration of their basic mechanical and technological properties, as well as the quality of castings' surfaces.
• the sandmix is characterized by very low harmfulness for the environment, since the loosening additive is inorganic mineral material, and its introduction also improves the sandmix's compliance to mechanical regeneration.
• Example 1 The moulding sandmix containing the following components:
• Example 2 The moulding sandmix containing the following components:
• Example 3 The moulding sandmix containing the following components:
• the tensile strength of a sandmix with geopolymer binder prepared without the loosening additive after 24 hours of rest is about 0.7 MPa. After heating the sandmix in temperature of 900°C the strength increases to about 0.85 MPa. On the other hand, the sandmix prepared of components mentioned in example 1, after 24 hours of rest was characterized by similar strength value, and after heating in temperature of 900°C the tensile strength rapidly dropped to the value less than 0.1 MPa.
• the compressive strength after 24 hours of rest of the sandmix with geopolymer binder, which was prepared without the loosening additive, is higher than 3 MPa.
• the sandmix prepared of components mentioned in example 1, after 24 hours of rest was characterized by similar strength value.
• the strength of sandmix with geopolymer binder after heating in the temperature of 900°C increases to about 5 MPa, while the strength of this sandmix prepared according to example 1, after heating in the temperature of 900°C rapidly drops to the value less than 0.1 MPa.
• Example 4 The moulding sandmix containing the following components:
• Example 5 The moulding sandmix containing the following components:
• Example 6 The moulding sandmix containing the following components:
• binder sodium water glass - 2,5 parts by weight liquid hardener: flodur (ester of ethylene glycol diacetate) - 8% parts by weight compared to the amount of binder loosening additive: pearlite ore with the main fraction 0,16 - 0,10 - 0,071 - 1,0 part by weight
• Example 7 The moulding sandmix containing the following components:
• binder sodium water glass - 2,5 parts by weight liquid hardener: flodur (ester of ethylene glycol diacetate) - 8% parts by weight compared to the amount of binder loosening additive: pearlite ore with the main fraction 0,16 - 0,10 - 0,071 - 2,0 parts by weight
• Example 8 The moulding sandmix containing the following components:
• the compressive strength after 24 hours of rest of the sandmix with geopolymer binder, which was prepared without the loosening additive, is higher than 3 MPa, and after heating in the temperature of 800°C it increases to about 5 MPa.
• the sandmix prepared according to example 8 after 24 hours of rest was characterized by similar strength value, and after heating in temperature of 800°C the tensile strength rapidly dropped to the value of 1.4 MPa

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Mold Materials And Core Materials (AREA)

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Citations (7)

• 2018
  • 2018-10-26 EP EP18202842.3A patent/EP3524372A1/fr not_active Withdrawn

Patent Citations (7)

Non-Patent Citations (4)

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