SU553035A1 - Non-stick paint for casting molds and cores - Google Patents

Description

(54) FIREPROOF PAINT FOR CASTING FORMS

And the rod of the chipboard spar (fluorite), which forms low-melting compounds, reducing the refractoriness and antiburning properties of the coating, as a rule, the paint is gassed. The aim of the invention is to provide the ability of the nonstick paint to self-solidify the molds and cores on the working surface and to reduce its gas creativeness. In order to achieve this goal, an adaptable non-stick paint for foundry molds and cores, including refractory filler, water and orthophosphoric acid, additionally contains hydrochloric acid and finely powdered substance selected from the following metal-containing compounds: copper, iron, zinc, these oxides metals, hydroxides of these metals, in a weight ratio in terms of pure metal with orthophosphoric acid 1: (B), in the following ratio of ingredients, weight. %: Water 23-33 Phosphoric acid (in terms of anhydrous product} 0.45-4.20 Salt-acid (in terms of conditional anhydrous product) 0.07-0.25 Finely powdered substance selected from the specified range of metal-containing compounds (in terms of pure metal) 0.15-0.7 Refractory fillerEverything. The content of acids in the composition is indicated in terms of anhydrous product. It is understood that acids of any concentration can be used. Depending on this, the composition should be recalculated their content is waterless For example, hydrochloric acid with a density of 1.149 g / cm of anhydrous product (HC6) contains 30%, the rest is water, and orthophosphoric acid with a density of 1.689 g / cm contains 85% H, PO, and the rest - water. Therefore, in order to prepare 1 kg of a paint containing 1.5% and 0.2% HCI, it is necessary to introduce acids of the indicated density in the amount of: orthophosphoric acid 1 OO 85 b 1000x0.2 6.66 brine 100 X 0 , 30 Water taken into account in acid solutions should be taken into account when dosing water in dye. It is preferable to use hydrochloric acid with a density of 1.10-1.19 g / cm and phosphoric acid - 1.25-1.85 g / cm. Hydrochloric acid provides fast and complete dissolution of metal powder, oxides or hydroxides. In its absence, the reaction of formation in living phosphates diminishes due to the formation of a film of poorly soluble reaction products on metal particles, oxides or hydroxides. Completely dissociating in water, hydrochloric acid ensures the constant presence of H ions in the solution, which contributes to the formation of acid phosphates in the dying substance. Being volatile, hydrochloric acid evaporates during the drying of the coating, and the remaining phosphates cement the layer. When the content of hydrochloric acid below the lower limit deteriorates the ability of the paint to self-hardening, and when its content is above the upper limit, the sanitary and hygienic working conditions deteriorate. The content of metal-containing compounds in the specified range is given in terms of pure metal. In this case, if oxide or copper, iron or zinc hydroxide is used as the metal-containing compound in the paint, the total content of this ingredient is determined by taking into account the gram-atom ratio of metal and oxygen in oxide or metal and hydroxyl in hydroxide. The experimentally found optimum ratio between metal and orthophosphoric acid 1: (3-b) makes it possible to obtain phosphates with high adhesion properties and, therefore, guaranteeing the formation of a durable coating at a low concentration in the composition. When the specified ratio is changed, as well as when the content of the metal-containing compound is below the lower and above the upper limits, the strength of the coating decreases after it hardens at 20 ° C, and in the latter case, the strength of the coating at 900 ° C. The filler can be used: crystalline or fused quartz, electrocorundum, chamotte, zircon, zirconium oxide. If the filler is obtained by grinding a pipe-like material using steel or cast-iron grinding media, metallic iron and its oxides are contained in it in the form of impurities in an amount of 0.1-1.0%. This impurity should be considered when determining the content of ingredients. Iron thus introduced, the particles of which were formed in the process of cleaving during grinding, is chemically highly active, since it has fresh chips, lattice defects, and unsaturated chemical bonds. The proposed composition can be used as a ready casting paint for molds and cores or as a basis for obtaining

such a paint. In the latter case, it is possible to additionally introduce various known additives with which the composition is well combined, for example graphite to obtain a reducing atmosphere, iron oxide to increase the thermal conductivity of the coating.

The rheological and structural properties of the proposed composition can be adjusted by small additions of surface-active substances (surfactants). With the help of surfactants, diluting the suspension, the permeability of the composition can be increased. Structuring surfactants increase its sedimentation stability and covering ability.

The proposed formulation is a suspension. It is prepared by moving all the components in a broom with a speed of 1200-2800 per minute for 3060 minutes. The coating layer on the mold or rod is confirmed both when it is dried at a temperature of 15 ° C-300 ° C, and under normal conditions. The coating is non-gaseous, has considerable strength at high temperature, does not form burns on the castings.

Example. A paint of the following composition is prepared (in wt.%): Water - 27.7, orthophosphoric acid - 1.02, hydrochloric acid 0.1 electrocorundum - 70.95, iron 0, 23, ratio Fe: IjPO 1: 4.4. A mixer with a speed of 2400 per minute is successively charged with 5 l of 850 ml of water, 15 O ml of orthophosphoric acid with a density of 1.7 g / cm, 50 ml of hydrochloric acid with a density of 1.17 g / cm, 15 kg of electrocorundum and 67.5 g of fine iron oxide containing 50 g of iron. Components are moved for 30 minutes. Dip-colored rods are dried in air for 30 minutes, then rods

put in a mold that is poured steel. The castings do not have a burn, there is no marriage for snakes and gas shells.

Samples for paint dyeing in cold and hot conditions were prepared as follows. Fluoroplastic plate with a recess of 40 x 20 x 3.5 mm was immersed in the paint. Then removed, allowed to drain the excess suspension. The resulting solution was dried for 2-3 hours under normal conditions. Then the deposition and drying operations were repeated. The four-layer sample had a thickness of 3.5-4.0 mm

After drying the fourth layer, the sample was removed from the substrate and tested for strength under static bending at 20 and 900 ° C on a ZIL design instrument.

The strength of paint samples in Example 1 is as follows: at 20 C - 18 kgf / cm, at 900 ° C - 24 kgf / cm -.

PRI mme R 2. The paint composition corresponds to that specified in Example 1 with the difference that powdered crystalline quartz of the brand KP-3, obtained by grinding of quartz sand in ball mills with steel balls, was used as a filler. Powdered quartz contains in its composition 0.315 weight .% fine metallic iron. The mixer is successively loaded: water — 5 l 85 O ml, orthophosphoric acid — 1 B O ml, hydrochloric acid — 50 ml. powdered silica containing iron - 15, O5 kg.

The strength of the specimens under bending at 20 ° C is 23.5 kgf / cm, and at 900 ° C 25.6 kgf / cm. The surface quality of the castings as in example 1.

PRI me R 3 Described in example 2, the method is used to prepare the proposed paint, as well as paint of known composition 5j. The compositions of the paints are given in the table.

Table

Water

Orthophosphoric acid (in terms of anhydrous product)

Sol Na Acid

/ in terms of anhydrous

product/

Chrome oxide

29.0

AOC

8.3

2.0

0.15

7.0

Powdered quartz containing 0.3 wt.% Iron

Dusty Quartz Both types of paint were dried to remove moisture at 70 ° C, other forms of paint were dried at 350 ° C for one hour. Gas content of paints / cm per 1 g of paint / as follows: Paint known (70 ° C) 24.0 (350 ° C) 10.4 Suggested paint (70 ° C) 5.2 (3500s) 1.3 Thus, the gas creativity proposed paint is 5-8 times lower than the known. PRI me R 4. Described in example 1, the method of preparing the paint of the following composition, weight. water - 27.3, orthophosphoric acid - 0.45 hydrochloric acid - O, 1, finely divided fused silica - 72.0, cuprous oxide in terms of pure copper - 0.15. Weight ratio CuHjPO 1: 3. The strength of specimens in bending at 20 ° C is 12 kgf / cm, and at 90 ° C it is 14 kgf / cm. EXAMPLE 5 In the manner described in example 1, the paint is prepared using the following composition (% by weight): water — 23, orthophosphoric acid — 4.2, hydrochloric acid — O, 1, fused silica — 7 2.0 , zinc hydroxide in terms of zinc -0.7O Weight ratio Zn iHaPO. 1: 6. Strength (. Samples at bending at 20-С-10 kgf / cm, and at 900 ° С - 35 kgf / cm. From the given examples it follows that the proposed compositions of nonstick coking paint provide self-hardening low-paint paints. Additional advantages of the proposed paint are its low cost.

67.85

Claims (5)

52.8 Claims of Invention Non-stick paint for casting molds and cores, including refractory filler, water, orthophosphoric acid, characterized in that, in order to self-harden it on the working surface of the molds and cores, reduce its gas creativeness, it additionally contains hydrochloric acid and fine powdered powder, selected from the following series of metal-containing compounds: copper, iron, zinc, oxides of these metals, hydroxides of these metals in a weight ratio in terms of pure metal with tofosfornoy acid 1: (3-b), with the following ratio of ingredients, wt. %: Water 23-33 Orthophosphoric acid (in terms of anhydrous product) 0.45-4.20 Salt-acid (in terms of conditional anhydrous product) 0.07-0.25 Finely powdered substance (in terms of pure metal) 0.15-0.70 Refractory Refill Else. Sources of information taken into account in the examination: 1. Literary production, 1974, №11, p. 22 2. Foundry production, 1973, No. 10, p. 35-36. 3. USSR author's certificate No. 400403, B 22 C 3/00, 1972 4. USSR author's certificate No. 415080, B 22 C 3/00, 1972 5. USSR author's certificate No. 407625, B 22 C 3/00, 1972