DK142152B - COVERING MATERIAL FOR PARTS OF PAPER MACHINES IN CONNECTION WITH MOVING WIRES OF SYNTHETIC MATERIAL - Google Patents

Description

142152

The invention relates to a coating material for parts of paper machines which are in contact with moving wires of synthetic material and having at least one smooth surface comprising hard particles embedded in a binder.

5 During the manufacture of paper, at a certain time, a damp, new paper web is passed from the "wet" section of the plant to the "dry" section and rests thereon on a conveyor belt of e.g. nylon fiber, polyester fiber or other kind of synthetic fiber.

The various parts of the plant which come into contact with the conveyor belt during its operation must necessarily be very durable without simultaneously slipping the belt up, and with the high speeds with which today it is driven this has become a more and more serious problem.

Furthermore, said parts are also subjected to influences from 15 water abrasive materials which are added inadvertently with the wood pulp, as well as other abrasive materials used to color and opalize the wood pulp during its conversion to paper.

The paper webs can be up to 8 meters wide and, consequently, the parts of the plant in contact with the conveyor belt will also become large and often complex in design, which makes replacing them a costly affair.

In the past, the wear-affected parts have been made of ceramic materials or with coatings thereof, but despite the great strength of these materials it has been desired to find new materials. The reason for this is that the ceramic surfaces cannot be repaired once damaged.

Attempts have also been made to grind off any pointed, protruding particles in the ceramic material, but even so, it has not succeeded in obtaining only rounded surfaces of the particles, without rather being faceted on their outward side.

In addition, a grinding could also expose deeper sharp particle tips, making the effort unsuccessful.

Coating of metal parts in contact with textile by chrome plating is a very good solution, if only the price had to be taken into account, because it is a costly solution which does not even provide high wear resistance.

High temperature flame spraying, e.g. detonation plating and plasma arc spraying can also be used to provide coatings consisting of metal oxides or metal-bound metal carbides, but it is difficult and almost impossible to obtain a uniform layer thickness. The prior art materials of the kind set forth in the preamble of claim 1 had some surface smoothness and abrasion resistance but were not repairable.

The material according to the invention is characterized by the part of claim 1 which is known in the drawing. This provides a more abrasion-resistant and more easily repairable material suitable for papermaking machines, the surface of which is more uniform and has a low coefficient of friction over most wire materials, and which is cheaper to both provide and maintain.

As stated in claim 2, it is achieved that the small particles can slip in between the larger ones, thus creating a high volume density for the hard phase at the wear surface, which is important, especially for sharp-edged machine parts.

15 Some of a machine part may consist of material with the large particles of sizes between 0.3 and 2.0 mm, but the rest of the part contains the small particles of 22 to 53µ. The material may contain particles of different sizes within said size ranges and in different proportions, provided that the surface roughness has a smaller RMS value than 20 1.778µ and greater than 0.025µ.

Ultimately, the particular purpose of using the machine part will determine the optimum size or sizes of the particles used.

Suitable wear-resistant particles for use in accordance with the invention include metal oxides, metal carbides, metal borides, metal nitrides and metal silicides in any mixture combination thereof. Examples of metal oxides include compounds such as alumina (AlgOg), silica (SiO4), chromium sulfide (Cr2 O3), hafnium oxide (HfO2), beryllium oxide (BeO), zirconia (ZrO2), stannic oxide (SnC> 2), magnesium oxide (MgO). ), 30 yttrium oxide (Y2 O2), rare earth oxides, and titanium oxide (TiC> 2) in any mixture. Suitable metal carbides include silicon carbide (SiC), boron carbide (B 1 ) and tungsten carbide (WC). Suitable metal borides include titanium boride (TiB2), zirconium boride (ZrB2), columium boride (CbB2), molybdenum boride (MoB2), tungsten boride (WB2), tantalum boride (TaB ,,), and chromium boride (CrB). Suitable metal nitrides include aluminum nitride (AiN), silicon nitride (Si 2 N 2), titanium nitride (TiN), zirconium nitride (ZrN), hafnium nitride (HfN), vanadium nitride (VN), niozine chromium nitride (CrN). Suitable silicides include molybdenum silicide (MOSI2), tantalum silicide (TaSi2), wool silicon titanium silica (TiSi2), zirconium silicon (ZrSi2) / vanadium silicon (VSI2) / niobium silicate (bbSil consists of a thermoplastic or curing resin capable of adhering to a metal or non-metal substrate and securely retaining partially embedded rounded wear resistant particles therein. The thickness of this binder layer should be at least approx. half the diameter of the largest particles or the average particle size so as to ensure good retention of the particles therein.

A coupling agent, which may be a silane or a silicon, can be applied to the particle binder mixture to increase the bond strength between the particles and the binder in the finished material, thereby providing a stronger material. Examples of coupling agents suitable for this purpose include vinyltriethoxysilane, beta- (3,4-epoxy-cyclohexyl) -ethyltrimethoxysilane, gamma-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, gamma-aminopropyltriethoxysilane and aminopropyl tree methoxysilane. An amount of the coupling substance 20 up to approx. 2% by weight (based on the weight of the particles) will be perfectly suitable for this purpose.

Example 1

A mixture of 50% by volume of 0.50-0.59mm polished 25 spherical alumina particles having a surface roughness of less than RMS value of 1.778µ and greater than 0.025µ and 50% by volume of thermosetting powder (polymethylmethacrylate powder, commercially known as "Type" 1385 AB Transoptic Mounting Powder "for metallurgical specimen assembly) was placed in a heated to 140 ° C form and kept at a pressure of 422 kg / cm for 10 minutes. The shape was approx. 25 mm in diameter and 29 mm long. After the 10 minutes of application of pressure at the elevated temperature, the mold was cooled to ambient temperature, after which the molded portion was removed from the mold. The 25 mm diameter and 29 mm long cylindrical portion exhibited a surface 35 of evenly distributed rotary ellipsoid alumina particles in the thermosetting resin.

Example 2

A single layer of alumina particles with a surface roughness of U2152 4 lower RMS value than 1.778µ and greater than 0.025µ of sizes from 0.50 to 0.59 mm was placed at the bottom of a cylindrical mold cavity measuring 32 mm in diameter. A thermosetting resin powder (polymethylmethacrylate powder "Type 1385 AB Transoptic Mounting Powder") was poured over this particle layer and then shaped as described in Example 1.

The thus formed portion consisted of a solid thermoset resin with a single layer of aluminum spheres on its surface.

Example 3 A base planar part for a Fourdrinier machine was made by bending a metal (aluminum) plate to a roughly channel-shaped appearance with a length of 106 mm, a width of 63 mm and legs of the length 32 mm. The leading edge of the surface as seen after the width dimension was bent upwards by approx. 2 ° from the surface and the leg here was curved 15 into an aerodynamic shape. Thus, as a fabric binder or the like is passed over such a support plane in a lateral direction, from the leading edge to the trailing edge, a differential pressure is drawn which sucks the liquid or other chemicals passing through the binder onto the posterior segment of the support surface, leaving the pulp or paper above. on tape 20 is dried.

The longitudinal ends of the carrier thus formed were coated with 13µ thick aluminum foil so as to form a closed channel shape with an opening at the top. 500 g of rotary ellipsoidal aluminum oxide particles of particle size 0.50 to 0.59 mm and having a surface roughness of lower RMS value than 1.778µ and greater than 0.025µ were added 600 g of epoxy resin known as "Araldite" 502.

The composition was mixed slowly as the particles were applied, thus reducing the formation of air bubbles in the mixture. The epoxy was very viscous and when / and if 30 air bubbles formed, they came to the surface. 60 g of liquid epoxy hardener, commercially known as "Araldite" 951, was added to the mixture and the composition was further mixed and then cured in the carrier form. Another portion of 600 g of "Araldite" 502 and 60 g of "Araldite" 951 were mixed and poured on top of the first mixture. The composition was allowed to harden for 24 hours. During the first 2 to 4 hours, the large epoxy mass became warm due to the exothermic reaction during polymerization. The revolving ellipsoid particles sank to the bottom of the mold, and the final product produced was a carrier having a top surface composed of specially sized ellipsoid particles embedded in an epoxy matrix.

A smaller cast occurred during curing because the epoxy ball layer and the pure epoxy layer shrunk differently. However, the composition prepared was sufficiently flexible to be stretched to the desired shape.

Example 4

A carrier mold was prepared as described in Example 3 except that the mold was made of steel. The cavity was 438 mm long, 63 mm wide and 35 mm deep. A "T" shaped core was provided to be placed in the cavity, so that a "T" shaped groove could be provided with a portion to be formed. The mold was surface cleaned and then sprayed with "Fluoroglide", a commercially available fluorocarbon abrasive. The mold was assembled and a small vibrator arranged to vibrate at 60 Hz was attached thereto.

A mixture of 250 g R8-2038 "Hysol" resin, 28 g H2-3416 "Hy-sol" hardener, 3 drops Union Carbide LS-46 silicone wetting agent and 356 g alumina spheres with 0.30 to 0.59 mm portion size and with a surface roughness of less than 0.254µ RMS and greater than 0.025µ was prepared and then poured into the mold while vibrating. A second mixture of 250 g R8-2038 "Hysol" resin, 20 g H2- 3416 "Hysol" hardener and 3 drops of LS-46 silicone wetting agent was prepared and 200 g of this composition was poured on top of the first mixture in the 25 vibrated form. The "T" shaped core was submerged in the epoxy and attached to the mold at its ends. The prepared material, after being cured at room temperature for 24 hours, was removed and exhibited a good carrier shape with a good particle distribution. Some air blisters could be seen on the surface and on certain parts of the leading edge.

30

Example 5 The carrier form and the "T" shaped core of Example 4 were used for this example. The mold was surface cleaned and then sprayed with a fluorocarbon such as type MS-122 from Miller-Stephenson 35 Company. A mixture of 250 g R8-2038 "Hysol" resin and 20 g H2-3416 "Hysol" hardener was stirred for 15 minutes. With the mold attached to a 60 Hz vibrator, the epoxy mixture was poured into the mold and then 350 g of 0.50 to 0.59 mm aluminum oxide particles with a surface roughness of less than RMS value of 1.778µ and greater than 0.025µ were poured. pi in the epoxy mixture. The "T" core b (possibly immersed in the mold, and then another epoxy mixture, prepared as above, was placed in the mold between the inner surface of the mold and the "T" shaped core. The mold content was cured at room temperature for 24 hours and the mixture was The produced carrier showed a surface with a good particle distribution, but the surface particle density was less than that produced in Example 4. Also, the surface of the carrier showed fewer blisters than the carrier surface of Example 4.

Example 6

The surfaces of a mold having internal dimensions of 76 mm x 25 mm and 19 mm high were cleaned and then sprayed with said type MS-122 fluorocarbon. 16.6 g of 0.30 - 0.59 mm aluminum oxide particles with a surface roughness of less than 0.254 µ RMS and greater than 0.025 µ 15 were poured into the mold attached to a 60 Hz vibrator. Aluminum oxide particles in an amount of 9.8 g and having a size of 0.053 mm and less were placed in the mold and on top of the first layer of particles while the mold was vibrated. A mixture of 30 g of "Hysol" resin R8-2308, 3.3 g of "Hysol" hardens H2-3416, 22 drops of "Union Carbide Corporation type 20 A-186 Silane" coupling fabric and 0.78 g of blue pigment of the type "Evercoat" "was stirred for 10 minutes and then poured into the mold. The mixture in the mold was cured at room temperature and then the composite was removed. The surface of the part showed good particle distribution with the smallest particles approximately filling the spaces between the larger particles.

Composite materials were also made using chromium oxide particles, chromium nickel-bound tungsten carbide particles, cobalt-bound tungsten carbide particles, and chromium carbide particles bound using an alloy of 20% nickel and 80% chromium. In the same way as in the 30 examples above, there was also a good particle distribution on the surfaces of these materials. Metal carbide particles are often bonded together by a metal or metal alloy binder. The above examples are metal-bound carbide particles.