SU900934A1 - Coating for reconditioning parts exposed to molten metal facing - Google Patents

Description

The invention relates to a foundry, in particular, to compositions of coatings for repairing parts by the method of surfacing with liquid metal.

Many of the paint compositions and coatings are known for painting the surface of casting molds, consisting of crushed chamotte, electrocorundum, apatite-nephelin ore, asbestos powder, refractory clay, bentonite, silvery graphite, expanded perlite, liquid glass, magnesium phosphate solution, sodium carboxymethyl sulfate. and other components 1, I21,31 and 4,

 The closest to the technical essence and the achieved result to the proposed is a paint for casting molds, containing wt.%: 8.0-12.0 expanded perlite 0.510, 0 pyrophyllite 0.05-3.5 refractory filler (silver graphite), 1 , 5-6,0 binder (sulfite-alcohol stillage) and water - the rest 5.

The disadvantage of this paint composition is that when the part is heated to a high temperature (1150-1300 K), sulfite-alcohol stillage is destroyed and when the liquid metal is poured into the mold, the coating is washed off the surfaces that are not subject to surfacing, and penetrated into the gap between the mold and the surface of the part is welded to the part and distorts its geometrical configuration. In addition, with prolonged heating to temperatures above 1250 K, expanded perlite begins

10 is sintered and melted, as a result of which the thermal insulating properties of the coating are reduced 1.5-2.0 times. An increase in the thermal conductivity of the coating leads to a decrease in heat loss in

15 by the process of nagreva of the weld surfaces and lengthening of the heating time. Lengthening the heat and the need to restore the geometric shape: parts leads to a decrease in the deposition rate of the cladding or to the restoration of the parts by pouring with liquid metal.

The purpose of the invention is to reduce heat loss from the heated surfaces of parts that are not subject to surfacing, to prevent metal from welding to these surfaces, to increase the heating rate and to increase the duration of the welding of parts. The goal is achieved by the fact that the coating, including expanded perlite, refractory filler, bon and water, additionally contains fine wood flour cement at the following ratio of ingredients, wt.%: Refractory filler12, 0-26 / 0 Expanded perlite of PVP brand according to PCT USSR 1344703, 0-10,5 Cement (GOST 970-77) 2.0-4.5 Fine wood flour (GOST 16361-70) 0.1-4.5 Binder3.0-7.0 WaterOriental As a binder Coating with holds liquid glass. As a refractory filler, the coating contains marshallite, electrocorundum, chamotte, or other materials that are incorporated into the composition of the coating to increase its refractoriness, eliminate the alloying of the coating and see the metal from the non-weldable surface. Optimal adhesion resistance of the coating begins to appear when its content is greater than 8.0 wt.% Of refractory per filling. With an increase in the content of the refractory filler more than 26.0 wt.%, Its thermal insulation properties deteriorate significantly. Expanded perlite (filter powder). has a grain size less than 0.16 mm, and a volume weight less than 200 kg / m. Its input into the composition of the coating provides the radiation of the necessary thermal insulation properties. The effect of the filter powder on the thermophysical properties of the coating is exhibited when it is introduced into the coating in quantities greater than 3.0 wt.%. With an increase in the content of the filter powder of more than 10.5 wt.%, The coating begins to show fusing and its thermal insulation properties deteriorate. Fine wood flour brand 140 and below is introduced to improve the thermal insulation properties of the coating. During induction heating of the weld surface, wood flour burns out in the coating of voids, which increase its thermal insulation properties. The effect of this component on the casting properties begins to appear when it is more than 0.1 wt.%. If the content of wood flour exceeds 4.5 wt. %, The coating loses its strength properties and is washed off with a molten liquid metal. Cement is introduced to cover the coating and accelerate solid liquid glass. The positive effect of cement is manifested when it is contained in the coating in quantities exceeding 2.0 wt.%. When its content is more than 4.5 wt.%, The coating has a low viscosity and is poorly applied to the surface of the part being protected. Liquid glass (GOST 16361-70, modulus 2.35-2.85, density 1.4----, 1.6 g / cm) is an inorganic binder that provides optimal coating ability and durability in a dried state. especially when pouring liquid metal into the mold. The minimum amount of water glass that provides the required properties is 3.0 wt.%. With an increase in its content of more than 7.0 wt.%, An increase in the viscosity of the coating is observed and its melting temperature decreases. Water provides the required density of the coating. D. To facilitate its application to the surface of the part. The compositions and properties of the proposed coating are given in table. 1 and 2. Studies have shown that the proposed coating, compared with the known composition, has a greater density (1.10-1.11 against 1.05-1.07 g / cm) and less sedimentation stability. In addition, the coating has high resistance to abrasion, tearing and shearing. The abrasion resistance increased from 84-96 to 104-116 g, the tensile strength of the coating layer from 0.03 to 0.0380, 052 MPa and the shear strength from 0.95 to 1.30-1.60 MPa. The lower degree of fusion of the coating of the proposed composition provides good heat insulating properties at high temperatures and thereby reduces the heating time of the track eyes when surfacing with liquid metal of the track and walking excavators to high temperatures from 52 to 3845 s and reduces their cooling rate after the end of heating. The cooling time of the lugs from 1300 to 1200 K is increased from 50 to 58-69 s. The presence of a relatively large amount of refractory filler eliminates the flushing of the coating with liquid metal (chromium iron) and the weld metal to planes that should not be deposited. This reduces the labor intensity of stripping and chipping of weld parts by 20-30%. Preliminary calculation of the expected economic effect from the introduction of the proposed coating composition

by increasing the heating rate of the weld surfaces by 7-12%, eliminating the metal weld in the non-welded places and reducing the cutting and cleaning works by 20-30%, it shows that savings will amount to 56.8 thousand rubles. for 6500 pcs. recoverable parts ..,

Table 1

Expanded. Perlite 2.75 9 grade PVP Pyrophyllite powder Marshallite Graphite silver Fine wood flour Cement Sulfite-alcohol bard y 1.1-1.2 g / cm Liquid glass m 2.35-1.85, 2.8 7 1 , 4-1.6 g / cm 81.67 -63 Strength of the coating layer by 0.0360.052 rupture, MPa Strength of the coating layer per cut, 1.60 0.5 6.0 3.0 10.75 10.0 7.0 22.0 26, and 26.5 0.1 1.5 3.0 4.8 4.5 2.0 3.2.25 4.65 5.75 3.0 4.5 5.0 2.0, 15 65.5 64.2548.3 78 0.049 0.038 0.041 0.0450.03 1.55 1.30 1.48 1.520.95

Heating time of the surface of the current lugs up to 1300 k, s

The cooling time of the surface of the eye:. track from 1300 to 1200 K

5-8

Claims (5)

No Invention Formula - 1. A coating for restoring elements that are exposed to the deposition of liquid metals, including expanded perlite, a refractory filler, bonding agent, and water, characterized in that, in order to reduce heat losses from the heated surfaces of parts not subject to surfacing, to prevent metal welding with these mi surfaces, at a variation of the heating rate and increase in the productivity of the surfacing of parts, the coating additionally contains fine wood flour and cement at the following corresponding ingredieit, wt.%: Refractory apolnitel12-26 Expanded perlite 3.0-10.5 Continued tabl, 2 44 42 45 52 61 59 58 50 No 17-26 Not Not No Cement 2.0-4.5 Fine wood 0.1-4.5 Flour Binder 3.0-7.0 Water Else 2. Coating pop.1, characterized in that it contains liquid glass as a bond , Sources of information, ntye taken into account in the examination 1. The author's certificate of the USSR 46012, cl. In 22 of 3/00, 1970. 2. Authors certificate of the USSR 51628, cl. In 22 of 3/00, 1970. 3. Authors certificate of the USSR 54933, cl. B 22 C 3/00, 1969. 4. USSR author's certificate 98322, cl. In .22 C 3/00, 197.2., 5. USSR author's certificate 33660, cl. B 22 C 3/00, 1977.