SU817020A1 - Method of producing refractory articles - Google Patents

Description

one

The invention relates to the production of electrofused bakor refractories.

There is a known method of manufacturing refractory products, including melting the charge, pouring the melt into molds and thermal processing of castings in a subordinate mode: holding for 2 hours, followed by cooling to 50–60 ° C per hour; holding at 1400 ° C for 8 hours followed by cooling to 10 ° C at a rate of 30 ° C per hour l.

The disadvantage of this method is the limited rate of cooling of the casting 50-60 ° C / h. This is due to the fact that the resulting elastic temperature stresses during the cooling process are amplified by residual stresses removed from the ductile state. In a number of cases, an increase in the cooling rate to 60-65 ° C / h leads to a deterioration in the quality of the product.

The closest to the technical essence and the achieved effect to the proposed is a method that includes annealing castings with a constant increase in the temperature of the medium at speeds of 250-300 degrees / h in the range of 20 ° C, 150-200 degrees / h in the range of 600-800 seconds, 60 -10Q deg / h in the range of 800-1200C. Isothermal holding is carried out at 1150-1200s for 3-4 hours. Further cooling is carried out at a speed of 40-60 degrees / h 2. Such an annealing mode ensures the alignment of the temperature gradients at the level of the conditional temperature limit of the material transition (bacor 33) elastic-fragile state (1150-1200C), which leads to a significant decrease in residual stresses.

Removing residual stresses to a minimum value allows an increase in the cooling rate in the elastic region of the casting material. However, this heat treatment is practically not

affects the improvement of the structure and the increase in the apparent density of the casting.

The purpose of the invention is to reduce the process of annealing castings and improve the quality of products.

The goal is achieved by the fact that the annealing is carried out in a water environment for 40-60 minutes, and then the castings released from the molds are placed in a thermostat, where the annealing of the castings is carried out in the following mode:

Claims (2)

Claim A method of manufacturing refractory products, mainly baddeleyite-alumina) comprising melting the mixture, pouring the melt into molds, annealing and cooling the castings, characterized in that, in order to reduce the technological process of annealing the castings and improve the quality 30 products, annealing is carried out in an aqueous medium at 100 ° C for 40-60 minutes, and then castings freed from molds are placed in a thermostat, where the annealing of the castings is carried out according to the following mode: temperature rise from 20 to 600'C at a speed of 200-300 ° C per hour at a pressure of 0.3 kg / cm ² ; from 600 to 800 ° C at a speed of 180-250 ° C per hour at a pressure of 0.3-0.6 kg / cm ^a ; from 800 4Q to 1180 ° C at a speed of 180-60 ° C per hour at a pressure of 0.6 -1.0 kg / cm ² followed by exposure at this temperature and pressure for 3-4 hours after which cooling is carried out according to the regime: temperature decrease from ₀ 45 1180 to 800 ° C at a speed of 180-200 per hour at an overpressure of (1-0.6) kg / cm ² ·; from 800 to 600 ° C at a speed of 90-100 ° C per hour at a pressure of (0.6 -0.3) kg / cm; from 600 to 5 “400 ° C at a speed of 50-60'C per hour at a pressure of (0.3-0) kg / cm ¹ ! from'400 to 200 ° C at a speed of 40-45's per hour from 200 to 20 ”C at a speed of 30-20 ° C per hour. 55 Sources of information taken into account in the examination 1. USSR Copyright Certificate No. 447391, cl. C 04 V 35/60, 1970. 2. Copyright certificate of the USSR $ 0 "592800, cl. C 04 V 35/60, -Ϊ975. ВНИИПИ 'Order 1225/31 Circulation 660 Subscription Branch of PPP Patent, g. "Uzhgorod, Project 4,