JPH04260629A - Roll for producing glass float - Google Patents

Abstract

PURPOSE:To improve corrosion resistance of glass conveying roll (a lift-out roll, a rear roll, etc.) to molten tin in a float glass production line. CONSTITUTION:The surface of a drum part (metal) (11) of a roll is coated with a flame sprayed film (12) of a Co-based alloy composed of 15-30% Cr, 5-16% Al, 0.1-1% Y and the remainder substantially composed of Co. Thereby, corrosion and sticking of tin with molten tin are hardly caused and a sound roll surface is maintained for a long period as compared with that of a conventional roll made of heat-resisting steel. As a result, effects such as improvement in roll useful life and reduction in maintenance thereby, improvement in line productivity and stabilization of glass quality can be obtained.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lift-out roll, a rare roll, etc. in a float glass production line.

0002

[Prior Art] In a float glass manufacturing line, molten glass is continuously supplied from a glass melting furnace to a molten tin bath, and as it floats forward on the surface of the tin bath, it forms a flat, smooth glass having a predetermined thickness and width. The ribbon is drawn out from the tin bath, supported from below by lift-out rolls, rare rolls, etc., and transported to the slow cooling zone. The glass ribbon immediately after being extracted from the tin bath has approximately 600
It is in a high temperature state of ~700°C, and the lift-out roll supporting it reaches a high temperature of 600-650°C, and the rare roll following it is also heated to a temperature of 300°C or higher. In addition, the surface of these rolls repeatedly comes into contact and non-contact with the glass ribbon as the roll rotates (circumferential speed is around 5 m/min, for example), and the surface that comes into contact with the glass ribbon changes as the width of the glass ribbon changes. Thermal stress (causing deformation of the roll) is generated on the roll surface due to temperature unevenness in the circumferential direction and the axial direction due to the widening and narrowing of the area. For this reason, conventionally, as the above-mentioned roll, the body part is HK
40 material (25Cr-20Ni-Fe) and HH material (13C
Those made of heat-resistant alloy steel, such as R-26Ni-Fe), are exclusively used.

0003

Problems to be Solved by the Invention In the actual use of the above-mentioned glass manufacturing rolls, the problem is that molten tin adheres to the underside of the high-temperature glass ribbon that is drawn out from the molten tin bath and is taken out of the bath. The molten tin contacts the surface of the body of the roll and corrodes the surface of the body. Molten tin is a substance that is extremely corrosive to metals.
Corrodes most metals. If the surface of the roll body becomes rough or uneven due to the adhesion of molten tin and the corrosion reaction,
The surface condition is transferred to the lower surface of the glass ribbon, and corrosion reaction products on the roll surface contaminate the glass ribbon, which causes problems such as deterioration of glass quality and yield.

[0004] Therefore, the above-mentioned roll requires careful care in managing the body surface during use, and the burden required for roll maintenance is large. If the rolls are replaced frequently in order to maintain a high level of stable glass quality, disadvantages such as a decrease in line productivity and an increase in costs are inevitable. In view of the above, the present invention provides a new roll that has less reactivity with molten tin, has improved corrosion resistance, and can maintain a smooth and beautiful surface over a long period of time.

[0005]

[Means for Solving the Problems] The roll for producing float glass of the present invention has Cr on the surface of the metal base material of the roll body.
: 15-30%, Al: 5-16%, Y: 0.1-1%
, a Co alloy thermal spray coating is formed, the remainder being essentially Co. The reasons for limiting the components of the thermal spray coating alloy formed on the surface of the body base material of the roll of the present invention are as follows.

Cr: 15-30% Cr not only improves molten tin corrosion resistance, but also activates Al and promotes stable formation of an Al2O3 film. At least 15% is required to achieve this effect. However, if the amount is too large, it will cause a decrease in ductility and deterioration of the matrix structure (for example, peeling off of the coating due to thermal shock), so 30%
is the upper limit.

Al: 5-16% Al is an element that forms Al2O3 film, and is a dense Al2O3 film forming element.
The formation of an O3 film provides stable corrosion resistance to molten tin. This requires at least 5%. However, an increase in Al is accompanied by a decrease in ductility, a decrease in the thermal expansion coefficient, etc., and causes difficulties in thermal spraying (for example, cracks during thermal spraying), so the upper limit is set at 16%.

[0008] Y: 0.1 to 1% The addition of Y to the Co-Cr-Al system
Effective in strengthening and suppressing peeling of oxide films such as 2O3. When Y is added in an amount exceeding the solid solubility limit, Co3Y preferentially precipitates at grain boundaries. In order to obtain the effect of strengthening the film and suppressing peeling, it is necessary to add Y exceeding the solid solubility limit. Therefore, 0.1%
The above shall apply. However, if added in a large amount, ductility decreases, so the upper limit is set at 1%.

Co: Balance Co has low reactivity to molten tin and is a stable element. By using Co as a balance component, excellent molten tin corrosion resistance is ensured.

Various known thermal spraying methods such as gas plasma spraying, water plasma spraying, jet coat spraying, and arc spraying may be applied to form the above-mentioned thermal spray coating. It is advantageous in that it can form a film with a high porosity (porosity of about 5% or less). The thickness of the sprayed coating may be about 0.1 to 1.5 mm.

[0011] The body base material may of course be made of heat-resistant alloy steel (HK40, HH, etc.) that has been used as the body material of conventional rolls, but in the present invention, the base material surface is made of the above-mentioned Co Since it is coated with an alloy film and does not come into direct contact with the glass ribbon or atmospheric gas, it does not require the same level of heat resistance required for conventional roll materials, so a lower grade alloy steel is used. It is also possible to do so.

FIG. 1 schematically shows the cross-sectional structure of the roll of the present invention. (11) is a body base material, and (12) is a Co alloy thermal spray coating formed as a surface layer of the body. (15, 15) is a shaft attached to the body. The roll of the present invention has a cylindrical body (for example, a centrifugally cast tube machined) made of an appropriate alloy steel as the body base material (11).
The roll shaft (15, 15) is attached to the body base material (
The surface of 11) is sandblasted as necessary to improve the adhesion of the thermally sprayed coating, and then the coating (
12) by thermal spraying and then grinding and polishing the film surface. The surface roughness of the film is
For example, Ra may be about 0.8 to 1.5 (μm).

[0013]

[Example] Heat-resistant alloy steel (0.43C-1.81Si-0
．． 87Mn-20.75Ni-24.52Cr-Fe,
Hollow cylindrical body (equivalent to HK40) (outer diameter: 85 mm,
A metal film was thermally sprayed on the surface of the sample (thickness: 5 mm, length: 100 mm), and the film surface was polished to produce a test material. As comparative examples, two hollow cylindrical bodies made of the same heat-resistant alloy steel as above were prepared, one in which the formation of a thermal spray coating on the surface was omitted, and another in which a metal coating of another type was thermally sprayed.

[0014] In Table 1, No. 1 to 6 are invention examples, No. 1
01 to 106 are comparative examples. Among the comparative examples, No. 10
1 is an example in which the formation of a thermal spray coating is omitted (equivalent to a conventional roll),
No. 102 and no. No. 103 is an example of a sprayed coating made of Ni alloy. No. 104 is an example in which a thermal spray coating with a composition equivalent to SUS310 stainless steel was formed. 105 and no. The thermal spray coating No. 106 is a Co-based alloy similar to the invention example, but the component content deviates from the specifications of the invention (No.
No. 105 has insufficient Cr content. 106 is an example of insufficient amount of Al. In the table, in the thermal spraying method column, "G" is gas plasma spraying, "J" is jet coat spraying, and "A" is arc spraying.

Each of the above test materials was immersed vertically in molten tin (approximately 20 mm deep) in a carbon box-shaped container, placed on the inner surface of the furnace wall of a molten tin bath furnace in a float line, and left for 80 days. Afterwards, the corrosion, tin adhesion, and cracks and
The presence or absence of peeling was observed, and the results shown in Table 2 were obtained. In the table, "○" in the corrosion reaction column indicates that the change in the surface of the sprayed coating due to corrosion is slight, and "×" indicates that the film surface deteriorates (roughening) due to corrosion.
The value in parentheses in the same column indicates the depth (mm) of the corrosion reaction layer on the substrate surface due to penetration of molten tin.
represents. Further, each mark in the column of tin adhesion indicates that the amount of tin adhesion is small in the order of "×→△→○" (○ indicates almost no adhesion).

[0016]

[Table 1]

[0017]

[Table 2]

As shown in the same table, N equivalent to the conventional material
o. No. 101 (HK40 cylindrical body, no thermal spray coating) was severely corroded by molten tin, and the corrosion reaction layer thickness (erosion depth) was also large. According to EPMA, the corrosion reaction layer is entirely N.
It is observed that the i component has eluted and the structure has changed to one in which Ni and Sn have been substituted. Furthermore, the surface has significant tin adhesion. No. 102~No. All of the thermal spray coatings No. 104 have poor corrosion resistance to molten tin, and as the coatings corrode, molten tin penetrates and a thick corrosion reaction layer is formed on the surface of the base material. On the other hand, invention example No.
．． Corrosion of the thermal sprayed coatings Nos. 1 to 6 and penetration of molten tin into the coatings are extremely slight, and tin adhesion to the coating surface is also extremely small. In addition, No. 105 and no. Corrosion and tin adhesion of the sprayed coating in No. 106 were reduced compared to other comparative examples, but inventive example No. It is not as good as 1 to 6.

[0019]

[Effects of the Invention] The float glass manufacturing roll of the present invention has extremely stable corrosion resistance against molten tin, has almost no tin adhesion on the surface, and maintains a smooth and beautiful surface condition for a long period of time. do. The improvement in the service life provides various effects such as a significant reduction in roll maintenance, improvement in line productivity, and high level stabilization of glass quality.

[Brief explanation of the drawing]

FIG. 1 is an axial cross-sectional view schematically showing the cross-sectional structure of the roll of the present invention.

[Explanation of symbols]

11 trunk base material, 12 thermal spray coating, 15 roll shaft.

Claims (1)

[Claims] Claim 1: The surface of the metal base material of the roll body is coated with Cr.
: 15-30%, Al: 5-16%, Y: 0.1-1%
. A roll for producing float glass, characterized in that the remainder is formed with a thermally sprayed coating of a Co alloy consisting essentially of Co.