CN111886649B

CN111886649B - Plate material for annealing treatment, method for producing plate material for annealing treatment, and method for producing substrate

Info

Publication number: CN111886649B
Application number: CN201980020329.5A
Authority: CN
Inventors: 桥本和明; 三浦正文
Original assignee: Hoya Corp
Current assignee: Hoya Corp
Priority date: 2018-03-30
Filing date: 2019-03-28
Publication date: 2022-08-05
Anticipated expiration: 2039-03-28
Also published as: JP6917520B2; CN111886649A; CN115116486A; JP7228007B2; WO2019189567A1; SG11202007984WA; JPWO2019189567A1; JP2021177440A

Abstract

The annealing plate material is used for annealing a plate-like blank, and is one of 2 or more plate materials stacked so as to sandwich the blank from both sides, and is characterized by having a pair of main surfaces at least one of which is in contact with the blank, and by having 1 or 2 or more through holes which are opened in the main surfaces and penetrate the plate material.

Description

Plate material for annealing treatment, method for producing plate material for annealing treatment, and method for producing substrate

Technical Field

The present invention relates to an annealing plate material used for annealing a material, a method for manufacturing the annealing plate material, and a method for manufacturing a substrate.

Background

Currently, a Hard Disk Drive (HDD) is incorporated in a personal computer, a DVD (Digital Versatile Disk) recording apparatus, and the like, for recording data. In a hard disk drive, a magnetic disk having a magnetic layer on a substrate is used, and magnetic recording information is recorded or read in the magnetic layer by a magnetic head that is slightly suspended from the surface of the magnetic disk. As the substrate of the magnetic disk, a metal substrate (aluminum substrate) or a glass substrate having a property of being less likely to undergo plastic deformation than a metal substrate or the like is suitably used.

For example, a magnetic disk glass substrate is produced by subjecting a plate-like glass material to mechanical processing such as grinding and polishing. Before the glass material is machined, annealing treatment may be performed to remove strain. As a conventional annealing treatment, a method of heat-treating a laminate in which a plate material called a setter plate and a glass material are alternately stacked is known (patent document 1). By performing such annealing treatment, not only strain removal but also flatness reduction of the glass material can be achieved, and the surface properties of the glass material can be improved.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 6238282

Disclosure of Invention

Problems to be solved by the invention

In the above conventional method, after the annealing treatment, the setter plates and the glass blanks are alternately taken out from the laminated body, thereby recovering the glass blanks. However, when the setter plate is removed, the glass material may be stuck to the lower surface of the setter plate and removed from the laminate together with the setter plate. In this case, in order to collect the glass material, an operation of separating (detaching) the glass material stuck to the setter plate from the setter plate is required, and therefore, the work efficiency is lowered and the productivity of the glass substrate is lowered. Further, the glass material stuck to the lower surface of the setter plate and lifted up may fall down to cause cracks, defects, or damage. The glass blank thus damaged is not suitable as a blank for a glass substrate, and the yield of the glass substrate may be lowered.

The invention aims to provide an annealing plate material, which can easily separate the laminated annealing plate material and a blank. Further, the present invention aims to provide a method for producing such an annealing plate material, and a method for producing a magnetic disk substrate using such an annealing plate material.

Means for solving the problems

One aspect of the present invention is an annealing-treated plate material used for annealing a plate-like blank, the plate material being one of 2 or more plate materials stacked so as to sandwich the blank from both sides,

having a pair of main surfaces, at least one of which is in contact with the blank,

the plate member is provided with 1 or 2 or more through holes which are opened in the main surface and penetrate the plate member.

The main surface preferably has an arithmetic average roughness adjusted so that air flows between the laminated plate material and the blank.

The sum of the arithmetic mean roughness of the main surface of the plate material and the main surface of the blank in contact with the main surface is preferably 0.2 μm or more.

The arithmetic mean roughness of the main surface of the plate material is preferably greater than the arithmetic mean roughness of the main surface of the blank in contact with the main surface.

The arithmetic mean roughness of the main surface of the plate is preferably 0.2 to 1.0. mu.m.

Preferably, at least one of the through holes is opened in the main surface of the plate material so that an edge of the plate material surrounding the at least one through hole is in contact with the main surface of the blank.

The through-hole opened in the main surface of the plate material is preferably circular in shape,

the diameter of the through hole is 1mm to 6 mm.

Preferably, the plate member has at least 2 through holes which are dispersedly opened in the main surface thereof.

When the main surface of the plate material is divided into 2 or more regions having an equal area, it is preferable that 2 or more through holes are arranged in the respective regions in the same number.

Preferably, the blank is provided with a position for forming a circular hole,

the through hole is opened in a region of the main surface of the plate material that is in contact with the portion of the blank where the position is set.

Preferably, the side wall of the plate material surrounding the through hole is chamfered so that a cross-sectional area of the through hole along a direction parallel to the main surface of the plate material increases as it approaches the main surface of the plate material.

Another aspect of the present invention is a method for manufacturing a plate material for annealing, the plate material being used for annealing a plate-shaped blank, the plate material being one of 2 or more plate materials stacked so as to sandwich the blank from both sides,

the sheet material having a pair of major surfaces, at least one of which is in contact with the blank,

the plate material is provided with 1 or 2 or more through holes which are opened in the main surface and penetrate through the plate material,

the above-mentioned manufacturing method comprises a molding treatment for molding the raw material powder of the plate material filled in the molding die,

the molding die has a protruding portion protruding from an inner wall surface of the molding die to form the through hole in the plate material.

Another aspect of the present invention is a method for manufacturing a substrate, including an annealing process in which at least 2 plate materials of the annealing-process plate material or the annealing-process plate material manufactured by the method for manufacturing the annealing-process plate material are laminated so as to sandwich a plate-shaped blank material from both sides, and the laminated body is heated to anneal the blank material.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the laminated annealing-treatment plate material and the blank can be easily separated.

Drawings

Fig. 1 is an external perspective view showing an example of an annealing plate material.

Fig. 2 is a sectional view showing the shape of the outer periphery of the plate material.

In fig. 3, (a) and (b) are views showing a state where the plate material is taken out from the laminated body.

In fig. 4, (a) to (d) are diagrams explaining the flow of air passing through the through-hole.

In fig. 5, (a) to (c) are diagrams for explaining another example of the flow of air passing through the through-hole.

Fig. 6 is a view showing a jig for attaching and detaching a plate material to and from the laminated body.

Fig. 7 is a cross-sectional view of the plate material in the vicinity of the through-hole.

Fig. 8 is a diagram showing a modification of the plate material.

Fig. 9 is a diagram showing another modification of the plate material.

Fig. 10 is a diagram illustrating an annealing process performed using the plate material of fig. 1.

Detailed Description

Next, the annealing plate material, the method for manufacturing the annealing plate material, and the method for manufacturing the magnetic disk substrate according to the embodiment of the present invention will be described in detail.

(sheet for annealing treatment)

The annealing treatment sheet material (hereinafter referred to as sheet material) of the present embodiment will be described. This embodiment includes various embodiments described later.

Fig. 1 shows a plate material 10 of the present embodiment.

The plate material 10 is one of 2 or more plate materials used for annealing a glass material as an example of a material. The plate material 10 is laminated so as to sandwich a plate-like glass material from both sides during the annealing treatment.

Sheet 10 has a pair of

major surfaces

1a, 1b, at least one of which is in contact with the glass blank. The

main surfaces

1a, 1b of the sheet material 10 are approximately circular. In the present specification, "approximately circular" includes perfect circles and ellipses, and the outer peripheral shape thereof may be constituted by only a circular arc having a single radius of curvature or may be constituted by a plurality of circular arcs having different radii of curvature.

The diameter of the plate 10 is, for example, 1.05 to 1.5 times the diameter of the glass material. Here, when the diameter of the plate material 10 is smaller than the diameter of the glass material, the outer peripheral portion of the glass material laminated on the plate material 10 is deformed along the end face on the outer peripheral side of the plate material 10 during the annealing process, and the outer shape of the plate material 10 is transferred to the glass material 20, whereby a trace (transfer trace) is formed on the main surface of the glass material, and the flatness of the glass material may be deteriorated. On the other hand, if the diameter of the plate material 10 is too large, the number of laminated bodies that can be arranged in a heating furnace (described later) during annealing treatment decreases, and the productivity of the glass material may decrease. Further, when the glass material and the plate material 10 are laminated, the amount of deviation of the center positions of each other becomes large, the center of gravity of the laminated body is shifted, stability is deteriorated, and the laminated body may be collapsed or inclined during conveyance. From this point of view, the diameter of the plate material 10 is preferably 1.05 to 1.2 times the diameter of the glass material 20.

The

main surfaces

1a, 1b of the plate material 10 are preferably larger than the main surfaces of the glass material so that the glass material laminated with the plate material 10 is not exposed from the

main surfaces

1a, 1 b. This makes it possible to reduce the flatness of the entire glass material, reduce the cutting margin of the glass material in the grinding process and the polishing process, and omit the grinding process and the polishing process. Therefore, the productivity of the glass substrate for a magnetic disk is improved.

To reduce the flatness of the glass blank, the flatness of the sheet material 10 is preferably less than the flatness of the glass blank. The flatness of the plate material 10 is, for example, 10 μm or less. The flatness was measured using a flatness measuring machine.

The coefficient of thermal expansion of the material of the sheet 10 is preferably close to the difference in the coefficient of thermal expansion of the material of the glass blank. If the difference between the thermal expansion coefficients of the sheet material 10 and the glass material is large, large stress is generated in the glass material during annealing due to the difference between the thermal expansion amount and the thermal contraction amount of the sheet material and the glass material, and the glass material may remain after annealing. Therefore, in the temperature range from the normal temperature to the annealing temperature, the ratio of the thermal expansion coefficient of the plate material 10 to the thermal expansion coefficient of the glass material is preferably 0.9 to 1.1. The coefficient of thermal expansion refers to the linear expansion rate measured by thermomechanical analysis in accordance with JIS R1618: 2002. In the case where the material of the glass blank 20 is aluminosilicate glass, the thermal expansion coefficient of the plate material 10 is, for example, 3 × 10 in a temperature region of 100 ℃ to 300 ℃ ^-6 /℃～10×10 ^-6 /℃。

The thermal conductivity of the material of the sheet 10 is preferably greater than the thermal conductivity of the material of the glass blank 20. By making the thermal conductivity of the plate material 10 large, heat can be sufficiently transferred to the glass material laminated with the plate material 10 at the time of annealing treatment. The thermal conductivity means a value calculated in accordance with JIS R1611: 2010. The thermal conductivity of the plate 10 is, for example, 1W/mK to 150W/mK at room temperature to 300 ℃.

Examples of the material of the plate material 10 include a metal oxide, a metal carbide, a metal nitride, a metal boride, and 2 or more kinds of these materials. Specific examples of these materials include alumina (Al) ₂ O ₃ ) Silicon carbide (SiC) and silicon nitride (Si) ₃ N ₄ ) Zirconium oxide (ZrO) ₂ ) Sialon (Si) ₃ N ₄ ·Al ₂ O ₃ ) Steatite, spinel, cordierite, and the like. Among them, alumina (Al) is preferably used ₂ O ₃ ) Silicon carbide (SiC).

The thickness of the plate 10 is, for example, 1mm to 3 mm. A specific example of the thickness of the plate 10 is 1.5 mm.

The end face shape of plate 10 may be a shape extending linearly perpendicular to

main surfaces

1a and 1b, or a shape chamfered at an end intersecting

main surfaces

1a and 1 b. The chamfered end face may have a cross-sectional shape shown in fig. 2, for example. Fig. 2 is a sectional view showing the outer peripheral shape of the plate material 10. In the example shown in fig. 2, the chamfered end portion has a shape curved in a convex shape with respect to the inside of the plate material 10, and the length L1 in the direction parallel to the

main surfaces

1a and 1b in the chamfered end portion is, for example, 0.2mm to 0.4mm, preferably 0.3 mm. The length L2 in the direction (plate thickness direction) orthogonal to the

main surfaces

1a and 1b of the chamfered end is, for example, 0.05mm to 0.2mm, preferably 0.1 mm.

As shown in fig. 1, the plate material 10 includes 1 or 2 or more through holes 2 that are open at the

main surfaces

1a, 1b and penetrate the plate material 10. Specifically, the through-hole 2 is opened at a position on the

main surfaces

1a and 1b where air flows into the gap between the laminated sheet material 10 and the glass material. By providing the plate material 10 with such through-holes 2, when the plate material 10 is taken out from the laminate 30 (see fig. 10) after the annealing treatment, air flows between the plate material 10 and the glass material 20 (see fig. 10) as described later, and the adhesion of the glass material 20 to the plate material 10 can be suppressed. From this aspect, the at least one through-hole 2 is provided such that the edge of the plate material 10 surrounding the open end of the at least one through-hole 2 abuts against the main surface of the glass material 20.

Fig. 3 (a) and (b) are views showing a state in which the plate material is taken out from the laminated body, fig. 3 (a) shows a case in which the conventional plate material 100 is used, and fig. 3 (b) shows a case in which the plate material 10 of the present embodiment is used.

In the conventional sheet material 100, no through-hole penetrating the sheet material 100 is provided, and when the sheet material 100 is lifted from the laminated body after the annealing treatment, as shown in fig. 3 (a), the glass material 20 is stuck to the lower surface of the sheet material 100 and lifted together with the sheet material 100. This is considered to be because the minute gap between the lower surface of the plate material 100 and the upper surface of the glass material 20 tends to be wide due to the self weight of the glass material 20, and the pressure of the gap is lower than the ambient pressure (atmospheric pressure). The more efficient the work of collecting the glass material 20 is required to be, the more rapidly the plate material 100 is attached and detached, the more the sticking of the glass material 20 is remarkably generated.

On the other hand, as shown in fig. 3 (b), since the plate material 10 of the present embodiment is provided with the through-hole 2, air can flow into the gap between the plate material 10 and the glass material 20 through the through-hole 2 when the plate material 10 is lifted up. Therefore, the glass material 20 is not stuck to the plate material 10, and only the plate material 10 is lifted up. In the example shown in fig. 3 (b), since the through-holes 2 are open to the atmosphere, air above the plate material 10 can flow into the lower side through the through-holes 2 when the plate material 10 is lifted. As described above, according to the present embodiment, adhesion of the glass material 20 to the plate material 10 can be suppressed, and separation of the plate material 10 and the glass material 20 can be easily performed. Therefore, the glass material 20 can be efficiently recovered. Further, the glass material 20 stuck to the plate material 10 can be prevented from falling.

Here, the flow of air passing through the through-hole 2 will be described with reference to fig. 4. In fig. 4 (a) to 4 (d), the flow of air passing through the through-hole 2 is shown by arrows, taking as an example a laminate in which the plate materials 10A, 10B, 10C and the glass materials 20A, 20B are alternately stacked on the base 60. The plate materials 10A to 10C are each provided with 2 through holes 2. In fig. 4 (a) to 4 (d), the main surfaces of the glass blanks 20A, 20B are exaggerated in surface roughness. In the present specification, the surface roughness means an arithmetic average roughness Ra (JIS B0601: 2001).

Between the main surface of the plate material and the main surface of the glass material facing each other, there is a gap due to the surface roughness of the plate material and the glass material, which communicates with the through-hole 2 of the plate material. Therefore, air can flow between the plate material 10A and the glass material 20A as indicated by the two arrows in fig. 4 (a). When the plate material 10A is lifted up, air can flow into the gap between the plate material 10A and the glass material 20A from above the plate material 10A through the through-hole 2. At this time, a flow of air flowing into the through-hole 2 from the side of the glass material 20A through the gap between the plate material 10A and the glass material 20A is also formed. When the plate material 10A is lifted up in this way, air flows between the plate material 10A and the glass material 20A, and thereby the adhesion of the glass material 20A to the plate material 10A can be suppressed.

Further, since the through-hole 2 of the plate material 10B communicates with the gap between the glass material 20A and the plate material 10B and the gap between the glass material 20B and the plate material 10B, air can flow as indicated by the two arrows in fig. 4 (B) in a state where the plate material 10A is taken out from the laminated body. Therefore, when the glass material 20A is lifted up, the plate material 10B is not stuck to the glass material 20A, and the glass material 20A can be taken out.

In addition, since air can flow in the state where the glass material 20A is taken out from the laminated body as shown by the double arrows in fig. 4 (c), the glass material 20B can be prevented from sticking to the plate material 10B when the plate material 10B is lifted up.

The through-hole 2 of the plate material 10C communicates with the gap between the glass material 20B and the plate material 10C, but when there is no gap between the plate material 10C and the base 60, no air flow is formed through the gap and the through-hole 2. Therefore, it is preferable to take measures to allow air to flow between the plate material 10C located at the lowermost layer of the laminated body and the base 60, as shown in fig. 5 (a) to 5 (C).

In the example shown in fig. 5 (a), the surface roughness of the main surface of the plate material 10C on the base 60 side is large, and air can flow as shown by the double arrows in fig. 5 (a) because a gap exists between the plate material 10C and the base 60. Therefore, when the glass material 20B is lifted up, the glass material 20B can be taken out without the plate material 10C adhering to the glass material 20B.

In the example shown in fig. 5 (b), the surface roughness of the surface of the base 60 is large, and a gap exists between the plate material 10C and the base 60, so that air can flow as indicated by the two arrows shown in fig. 5 (b). Therefore, when the glass material 20B is lifted up, the glass material 20B can be taken out without sticking the plate material 10C to the glass material 20B.

In the example shown in fig. 5 (c), a hollow area S is formed in a portion including the surface of the base 60. The hollow region S communicates with the through hole 2 of the plate material 10C and with the space on the outer peripheral side of the plate material 10C. Therefore, air can flow as indicated by the two arrows shown in fig. 5 (c). Therefore, when the glass material 20B is lifted up, the glass material 20B can be taken out without the plate material 10C adhering to the glass material 20B.

The air flowing through the gap and the through-hole 2 described above is not limited to air in the atmosphere communicating with the gap and the through-hole 2, and may be air supplied from outside different from the atmosphere. Such air can be supplied, for example, by using a jig 50 (see fig. 6) for attaching and detaching the plate material 10. Fig. 6 is a view showing the jig 50 for taking out the plate material 10 and the glass material from the laminated body. The jig 50 includes a suction pad 51 and a suction mechanism, not shown, and can convey the plate material 10 while sucking the main surface thereof to the suction pad 51. The jig 50 includes a supply mechanism, not shown, that supplies air to the through-hole 2. By supplying air from the jig 50 to the through-hole 2, the air flows into between the plate material 10 and the glass material 20 in contact with the plate material 10 through the through-hole 2, and when the sucked plate material 10 is lifted up, the adhesion of the glass material 20 to the plate material 10 can be suppressed, and the plate material 10 and the glass material 20 can be easily separated.

According to one embodiment, the sum of the arithmetic average roughness Ra1 of the main surface of the plate material 10 and the arithmetic average roughness Ra2 of the main surface of the glass material 20 in contact with the main surface is preferably 0.2 μm or more. When the total of the arithmetic mean roughness is 0.2 μm or more, a sufficient gap can be secured between the laminated sheet material 10 and the glass material 20, and therefore air can flow into the gap between the sheet material 10 and the glass material 20 through the through-holes 2, and adhesion to the glass material 20 and the sheet material 10 can be suppressed. The arithmetic mean roughness Ra was measured by a stylus type roughness meter (contact roughness measuring machine) using a stylus (stylus).

In this embodiment, according to a further embodiment, it is preferable that Ra1> Ra2 is satisfied. By satisfying such a relationship, the effect of suppressing the adhesion of the glass material 20 to the plate material 10 increases.

According to one embodiment, the arithmetic average roughness Ra1 of the main surface of the sheet material 10 is preferably 0.2 μm to 1.0. mu.m. When Ra1 is less than 0.2 μm, air is less likely to pass between the plate material 10 and the glass material 20, and the glass material 20 is likely to be stuck to the plate material 10, so that the operation of removing the glass material 20 from the plate material 10 takes time, and the work efficiency is likely to be lowered. In addition, if Ra1 is less than 0.2 μm, the manufacturing cost of the plate material 10 for reducing the arithmetic average roughness increases. On the other hand, when Ra1 exceeds 1.0 μm, the particles may be detached from the plate material 10 to generate dust due to the contact between the glass material 20 and the plate material 10. Particles detached from the sheet material may adhere to the surface of the glass material 20, contaminate the glass material 20, and damage the surface of the glass material 20. In addition, when Ra1 exceeds 1.0 μm, particularly 1.3 μm or more, a special step for increasing the arithmetic mean roughness is required, and the manufacturing cost of the plate material 10 increases. The preferred arithmetic mean roughness Ra1 of the main surface of the plate material 10 is, for example, 0.6 μm.

The arithmetic mean roughness Ra2 of the main surface of the glass material 20 is, for example, 0.001 to 1.3 μm. A preferable specific example of the arithmetic average roughness Ra2 is 0.7. mu.m.

According to one embodiment, the through-holes 2 that open onto the

main surfaces

1a, 1b of the plate material 10 are circular in shape, and the diameter of the through-holes 2 is preferably 1mm to 6 mm. When the diameter of the through-hole 2 exceeds 6mm, the glass material 20 laminated with the plate material 10 is deformed so as to slightly enter the through-hole 2 during the annealing treatment, the opening shape of the through-hole 2 is transferred to the glass material 20, and a trace (transfer trace) may be generated on the main surface of the glass material 20. Therefore, the flatness of the glass material 20 may be deteriorated. Such a glass blank 20 with marks is easily unsuitable as a blank for a glass substrate for a magnetic disk. If the diameter of the through-hole 2 is less than 1mm, air is less likely to flow between the plate material 10 and the glass material 20, and the flow of air is likely to be deteriorated. Therefore, it takes time to separate the glass material 20 from the plate material 10, and the work efficiency may be reduced. If the diameter of the through-hole 2 is less than 1mm, the manufacturing cost of the through-hole 2 increases. The diameter of the through-hole 2 is more preferably 2mm to 5 mm.

According to one embodiment, the glass blank 20 is set with a position where a circular hole is formed (circular hole forming position). The circular hole is, for example, a circular hole concentric with the outer periphery of the glass material 20. In this case, the through-hole 2 is preferably provided in a region of the

main surfaces

1a and 1b of the plate material 10 that is in contact with the portion of the glass material 20 where the round hole forming position is set. If the through-hole 2 is provided in such a region, even if a transfer mark is formed on the glass material 20, the transfer mark is removed from the glass material 20, and therefore, the effect of the transfer mark of the glass material 20 is not exerted. The round hole forming position is set at a portion including the center of the main surface of the glass material 20.

According to one embodiment, as shown in fig. 7, the side wall 3 of the plate material 10 surrounding the through-hole 2 is preferably chamfered so that the sectional area of the through-hole 2 along the direction parallel to the

main surface

1a or 1b of the plate material 10 (the left-right direction in fig. 7) increases as it approaches the

main surface

1a or 1b of the plate material 10. Fig. 7 is a cross-sectional view of the plate material 10 in the vicinity of the through-hole 2. In the example shown in fig. 7, the portion of the side wall 3 of the chamfered plate material 10 has an inclined wall surface 3a inclined with respect to the plate thickness direction of the plate material 10. By chamfering the side walls 3 of the plate material 10 in this way, when the glass material 20 is deformed with the above-described transfer marks during the annealing treatment, the amount of deformation can be reduced, and deterioration in the flatness of the glass material 20 can be suppressed. Such an inclined wall surface 3a is effective when the through-hole 2 is provided in the region of the

main surfaces

1a, 1b of the plate material 10 that is in contact with the portion of the glass material 20 other than the round hole forming position. The inclination angle of the inclined wall surface 3a with respect to the direction in which the wall surface of the side wall 3 other than the inclined wall surface 3a (the wall surface between the inclined wall surfaces 3a on both sides) extends is preferably 30 ° to 60 °, for example, 45 °. The cross-sectional shape of the portion of the sidewall 3 of the chamfered plate material 10 is not limited to the linear shape shown in fig. 7, and may be curved or bent in a convex or concave shape toward the inside of the through-hole 2.

According to one embodiment, preferably, there are 2 or more through holes 27, which are dispersedly opened in

main surfaces

1a, 1 b. This suppresses an increase in the effect of sticking the glass material 20 to the plate material 10. The number of the through holes 2 is, for example, 1, 2, 3, 4, or 5 or more.

In the case where the

main surfaces

1a and 1b of the plate material 10 are divided into 2 or more regions having the same area, the same number of through holes 2 are preferably arranged in each of the 2 or more regions, and for example, 1 through hole 2 is preferably arranged in each of the regions, as shown in fig. 8, for the 2 or more through holes 2. Fig. 8 is a diagram showing a modification of the plate material 10. In the example shown in fig. 8,

main surfaces

1a and 1b of plate material 10 are divided into 4 regions by two imaginary lines (broken lines) perpendicular to the centers of

main surfaces

1a and 1b, and 1 through-hole 2 is arranged in each region.

On the other hand, if the number of through holes 2 is increased, the possibility of occurrence of transfer marks in the glass material 20 is increased. Therefore, the preferable number of the through holes 2 provided in the plate material 10 is 1 to 4. In this embodiment, as described above, it is also preferable that the through-hole 2 be provided in the regions of the

main surfaces

1a and 1b that are in contact with the portion of the glass material 20 where the round hole forming position is set. It is also preferable to reduce the opening area of each through-hole 2 or the total opening area of the through-holes 2.

The opening shape of the through hole 2 of the plate material 10 is not limited to a substantially circular shape, and may be a polygonal shape, a shape extending in one direction or a plurality of directions along the extending direction of the plate material 10, or the like. As an example of the shape extending in one direction, as shown in fig. 9, there is a shape extending along the circumferential direction of the plate material 10. Fig. 9 is a diagram showing another modification of the plate material 10. Examples of the shape extending in a plurality of directions include a shape extending in 3 or more directions (for example, a Y-shape or a cross-shape).

The extending direction of the through-hole 2 is not limited to the direction parallel to the plate thickness direction, and may be a direction inclined with respect to the plate thickness direction. The through-hole 2 may extend in a bent or curved manner between portions on both sides in the extending direction of the through-hole 2.

The plate material 10 described above may be used for annealing of a material other than a glass material such as an aluminum material.

(method of producing sheet Material)

Next, a method for manufacturing the plate material of the present embodiment will be described. This embodiment mode includes various embodiment modes described later.

The method for manufacturing a plate material is a method for manufacturing one of 2 or more plate materials that are used for annealing a glass material and are stacked so as to sandwich a plate-shaped glass material from both sides.

The plate material has a pair of main surfaces, at least one of which is in contact with the glass material, and 1 or 2 or more through holes that are open in the main surfaces and penetrate the plate material. That is, the plate material is the same as the plate material 10 described above.

The manufacturing method comprises a molding treatment for molding the raw material powder of the plate material filled in the mold for molding.

The molding die has a protruding portion protruding from an inner wall surface of the molding die to form a through hole in the plate material.

According to the present manufacturing method, a plate material having a through-hole can be manufactured by a molding process, and the plate material can be manufactured at a lower cost than a case where a through-hole is provided by punching a blank plate of a plate material having no through-hole. For example, a plate material made of the metal compound is hard, and a drilling operation using a tool such as a drill or a laser is costly.

In the molding treatment, for example, after molding by Cold Isostatic Pressing (CIP), degreasing and sintering may be performed. The sintering may be performed by an atmospheric pressure sintering method, preferably a gas pressure sintering method, or a Hot Isostatic Pressing (HIP) method after sintering.

By using the above method for producing a plate material, a plate material used for annealing a material other than a glass material such as an aluminum material can be produced.

(substrate for magnetic disk)

Next, the magnetic disk substrate of the present embodiment will be described. The present embodiment is suitable for manufacturing a glass substrate for a magnetic disk having a nominal size of 2.5 inches to 3.5 inches (diameter of 65mm to 95mm), a plate thickness of 0.1mm to 1.5mm, and preferably a plate thickness of 0.3mm to 0.9 mm.

The magnetic disk glass substrate has a disk shape. The magnetic disk glass substrate may have a ring shape in which a circular center hole concentric with the outer periphery of the magnetic disk glass substrate is hollowed out. Magnetic disks are formed by forming magnetic layers (recording regions) in annular regions on both surfaces of a magnetic disk glass substrate.

(blank for magnetic disk)

A magnetic disk glass material (hereinafter, simply referred to as a glass material), which is an example of a magnetic disk material, is a glass plate produced by press molding treatment and is a glass plate before grinding treatment described later. The glass material is not limited to being produced by press molding, and may be produced by a method such as float process or fusion process. The shape of the glass blank is approximately circular. The glass material may have a circular hole formed by a circular hole forming process described later.

As a material of the glass blank, aluminosilicate glass, soda-lime glass, borosilicate glass, or the like can be used. In particular, since chemical strengthening can be performed and a glass substrate for a magnetic disk excellent in flatness of the main surface and strength of the substrate can be produced, aluminosilicate glass can be suitably used.

(method of manufacturing magnetic disk substrate)

Next, a method for manufacturing a magnetic disk substrate according to the present embodiment will be described. The present embodiment includes various embodiments described below.

First, a glass material is produced by press molding a molten glass gob, which is a material of a plate-shaped magnetic disk glass substrate having a pair of main surfaces (press molding treatment). Next, a heat treatment (annealing treatment) for removing strain of the glass blank is performed. After the annealing treatment, a circular hole is formed in the center portion of the glass material to form a ring shape (circular ring shape) (circular hole forming treatment).

Next, the glass material is subjected to shape processing (shape processing treatment) by end face grinding. Thereby, a ring-shaped (annular) glass substrate is produced. Next, main surface grinding (grinding process) is performed using fixed abrasive grains, and end face polishing (end face polishing process) is performed on the flat glass substrate. Next, the first polishing (first polishing process) was performed on the main surface of the glass substrate. Next, the glass substrate is chemically strengthened (chemical strengthening treatment) as necessary. Next, the chemically strengthened glass substrate is subjected to the 2 nd polishing (2 nd polishing treatment). The glass substrate for a magnetic disk was obtained through the above-described treatment. Hereinafter, each process will be described in detail.

(a) Compression molding treatment

The molten glass stream is cut by a cutter, and the cut molten glass gob is sandwiched between pressing surfaces of a pair of molds and pressed to form a glass material. In the present embodiment, as will be described later, the glass material is molded by dropping the front end of the molten glass flow onto the upper surface of the lower mold, cutting the molten glass flow at the upstream side thereof to form a molten glass gob, and pressing the molten glass gob from above to below with the upper mold.

After pressing for a predetermined time, the mold was opened, and the glass material was taken out.

(b) Annealing treatment

In the annealing treatment, a laminated body in which a glass material is laminated by sandwiching the glass material from both sides using 2 or more plate materials is heated to anneal the glass material. The plate 10 described above was used as the plate. Specifically, as shown in fig. 10, the laminated body is formed by alternately stacking the plate material 10 and the glass material 20. The number of plate materials 10 is 1 more than the number of glass blanks 20 (for example, 10 to 30), and is disposed at a position including the uppermost layer and the lowermost layer of the laminated body 30. The laminate 30 is subjected to annealing treatment by applying a load to the uppermost layer and maintaining the temperature in the heating furnace 40.

(c) Round hole forming process

A circular hole (circular hole) is formed in the glass material by coring, scribing, or the like, thereby obtaining a disk-shaped glass material with a circular hole.

The coring method comprises the following steps: the glass material is cut from one main surface by a cylindrical core drill having one end open, thereby cutting a circumferential portion of a circular hole and digging out glass in the center portion (core) to form a through hole. The circular cutting line (outer circle) to be the outer contour of the glass material may be cut by core drilling at the same time as the circumferential portion (inner circle) of the circular hole is cut. Then, the outer portion of the outer circle and the inner portion of the inner circle of the glass material were removed to obtain a disk-shaped glass material.

The scribing is the following method: a circular cutting line is provided on one main surface of a glass blank by a cutter (scriber) made of cemented carbide or made of diamond particles, and then the glass blank is heated to stretch the circular cutting line in the thickness direction of the glass blank and to press the inside of the circular cutting line for separation. The circular cut line to be the outer contour line of the glass material may be formed simultaneously with the circular cut line to be the circular hole contour line. In this case, the circular cutting line (outer circle) which is the outer contour of the glass material and the circular cutting line (inner circle) which is the contour of the circular hole are formed to be concentric circles. Then, the glass material is partially heated, and the outer portion of the outer circle and the inner portion of the inner circle of the glass material are removed by the difference in thermal expansion of the glass material, thereby obtaining a disk-shaped glass material.

(d) Shape processing treatment

In the shape processing, the outer peripheral end of the glass material is chamfered. When a round hole is formed in the glass material, the inner peripheral end of the round hole is also chamfered.

(e) Grinding treatment

In the grinding process, the main surface of the glass material is ground using a double-side grinding apparatus provided with a planetary gear mechanism. Specifically, the outer peripheral side end face of the glass material is held in a holding hole provided in a holding member of a double-side grinding apparatus, and both main surfaces of the glass material are ground. The double-side grinding apparatus has a pair of upper and lower surface plates (upper surface plate and lower surface plate), and a glass substrate is held between the upper surface plate and the lower surface plate. Further, by moving either or both of the upper platen and the lower platen and moving the glass material and the platens relative to each other, the both main surfaces of the glass material can be ground, and the plate thickness can be adjusted to further improve the flatness.

(f) End face grinding treatment

In the end face polishing process, the end face of the outer peripheral side of the glass substrate obtained by the grinding process of the glass blank is mirror-polished by brush polishing. In the case where the glass substrate is formed with the circular hole, the inner peripheral side end surface of the circular hole is also mirror-polished. At this time, abrasive grain slurry containing fine particles of cerium oxide or the like as free abrasive grains is used.

(g) 1 st grinding treatment

The 1 st polishing process is intended to remove flaws and strain remaining on the main surface during grinding with fixed abrasive grains, or to adjust minute surface irregularities (microwaviness, roughness), for example. Specifically, the outer peripheral end face of the glass substrate is held in a holding hole provided in a polishing carrier of a double-side polishing apparatus, and the main surfaces on both sides of the glass substrate are polished.

In the 1 st polishing process, a double-side polishing apparatus having the same configuration as that of a double-side polishing apparatus used in a polishing process using fixed abrasive grains was used to polish a glass substrate while supplying a polishing slurry. In the 1 st polishing process, unlike grinding with fixed abrasive grains, a polishing slurry containing free abrasive grains is used instead of the fixed abrasive grains.

As with the double-side grinding apparatus, the double-side grinding apparatus has a pair of upper and lower surface plates (upper surface plate and lower surface plate), and a glass substrate is held between the upper surface plate and the lower surface plate. An annular flat polishing pad (e.g., a resin polishing material) is mounted on the entire upper surface of the lower surface plate and the bottom surface of the upper surface plate. The glass substrate and the respective surface plates are relatively moved by moving either or both of the upper surface plate and the lower surface plate, thereby polishing both main surfaces of the glass substrate.

The glass substrate after the 1 st polishing treatment can be chemically strengthened (chemical strengthening treatment) by immersing the glass substrate in a chemical strengthening solution. As the chemical strengthening liquid, for example, a molten mixture of potassium nitrate and sodium sulfate can be used.

(h) 2 nd grinding (final grinding) treatment

The purpose of the 2 nd polishing process is mirror polishing of the main surface. In the 2 nd polishing, a double-side polishing apparatus having the same configuration as that of the double-side polishing apparatus used in the 1 st polishing was also used. Specifically, the outer peripheral end face of the glass substrate is held in a holding hole provided in a polishing carrier of a double-side polishing apparatus, and the main surfaces on both sides of the glass substrate are polished. The 2 nd polishing process differs from the 1 st polishing process in that the hardness of the resin polishing material differs depending on the kind and particle size of the free abrasive grains. Specifically, a polishing liquid containing colloidal silica having a particle size of about 5nm to 100nm as free abrasive grains is supplied between a polishing pad of a double-side polishing apparatus and a main surface of a glass substrate, and the main surface of the glass substrate is polished. The polished glass substrate is cleaned with a neutral cleaning agent, pure water, isopropyl alcohol, or the like, thereby obtaining a glass substrate for a magnetic disk.

In the method for manufacturing a glass substrate for a magnetic disk of the present embodiment, since the plate material 10 having the through-holes 2 is subjected to the annealing treatment, the plate material 10 and the glass material 20 can be easily separated after the annealing treatment, and the glass material 20 can be efficiently recovered. Therefore, the productivity of the glass substrate for a magnetic disk is also improved. Further, when the plate material 10 is taken out after the annealing treatment, the glass material 20 can be prevented from falling. This can suppress a blank unsuitable for a magnetic disk glass substrate, and can suppress a reduction in the yield of the magnetic disk glass substrate.

By using the above-described method for producing a substrate, substrates other than a glass substrate for a magnetic disk, such as an aluminum substrate for a magnetic disk, can be produced.

(Experimental example)

In order to examine the effects of the plate material of the present embodiment, annealing treatment was performed using plate materials and glass blanks of various specifications.

In the annealing treatment, the laminate was assembled by combining a plate material and a glass material having the specifications shown in tables 1 to 3 below. In each sample, 61 sheets of the same-size plate material and 60 sheets of the same-size glass blank were alternately arranged one by one on a base to assemble a laminated body, a 500g weight was placed on the uppermost plate material, and annealing treatment was performed in a heating furnace 40 shown in FIG. 10 under heat-retaining conditions of 500 to 550 ℃ for 30 to 120 minutes. The plate material and the base disposed in the lowermost layer are in the form shown in fig. 5 (b).

As the plate materials of samples 1 to 25, approximately circular aluminum oxide plate materials having a diameter of 110mm were used.

The through hole of the plate material is positioned on the main surface inside a circle concentric with the outer periphery of the plate material and having a diameter half the length of the plate material diameter. The through-hole has a shape extending in a cylindrical shape in the plate thickness direction.

As the glass material, a glass material made of approximately circular aluminosilicate glass having a diameter of 100mm was used. In addition, the glass materials of samples 21 to 23 were glass materials produced by the float process, and the glass materials of the other samples were glass materials produced by the press molding treatment.

After the annealing treatment, the number of times of generation of sticking, the number of generation of transfer marks, and the number of pieces of contaminated glass material were counted as follows.

(1) Number of times of pasting

When the plate materials are sequentially attached and detached one by one from the plate material located at the uppermost layer, the number of times the glass material is stuck is designated as a when less than 3 times among 60 times, B when 3 times or more and less than 10 times, and C when 10 times or more, and a and B are evaluated as being able to inhibit sticking, and C is evaluated as being unable to inhibit sticking. The loading and unloading of the panels takes place in half the time normally required.

(2) Number of transfer marks

When the main surfaces on both sides of 60 glass blanks were visually observed, the number of transfer marks caused by through holes was found to be a + when 60 glass blanks were smaller than 3, to be a when 3 or more and smaller than 5, to be B when 5 or more and smaller than 10, to be C when 10 or more and smaller than 15, and to be D when 15 or more, and a + to C were evaluated as being able to suppress the transfer marks, and D was evaluated as being unable to suppress the transfer marks.

(3) Number of contaminated glass blanks

The main surfaces and end faces on both sides of 60 glass blanks were observed with an oblique incidence interference flatness tester (FT-17 manufactured by NIDEK corporation), and the number of glass blanks to which particles having a size of 1 μm to 100 μm generated from a plate material were attached was a when the number of glass blanks was less than 5 in 60, B when the number of glass blanks was 5 or more and less than 10, and C when the number of glass blanks was 10 or more, and a and B were evaluated as being capable of suppressing contamination of glass blanks, and C was evaluated as being incapable of suppressing contamination of glass blanks.

The results are shown in tables 1 to 3.

[ TABLE 1 ]

[ TABLE 2 ]

[ TABLE 3 ]

As is clear from comparison of samples 6 to 25 with samples 1 to 5, sticking can be suppressed by providing the plate material with the through-holes. In samples 22, 23, and 25, it was found that the number of times of sticking was generated was evaluated as B, and it was possible to suppress sticking when the experiment was performed under the same conditions except that the time (usually required time) required for attaching and detaching the plate material was about 2 times longer. On the other hand, in samples 4 and 5, it was found that it took about 2 times as long time to attach and detach the plate material, and experiments were performed under the same conditions except for this point, and as a result, the number of times of occurrence of sticking was evaluated as C, and it was not possible to suppress sticking.

From the results of samples 6 to 10, it is understood that the smaller the number of through holes and the smaller the hole diameter of the through holes, the greater the effect of suppressing the transfer mark. In particular, when the number of through holes is 2 or less, or when the hole diameter of the through holes is 6mm or less, the effect of suppressing the transfer marks is particularly large. The same results were obtained for samples 11 to 15 and samples 16 to 20.

It is clear from comparison of samples 1 to 3 with samples 4 and 5 that the number of contaminated glass blanks can be suppressed by reducing the arithmetic average roughness Ra1 of the main surface of the plate material.

In samples 9, 14, and 19, the plate materials were annealed while changing the diameters thereof to 95mm, and 90mm, respectively, and as a result, 15 or more transfer marks were generated in 60 sheets in all the samples.

The annealing-treated plate material, the method for producing the annealing-treated plate material, and the method for producing the substrate of the present invention have been described above in detail, but the present invention is not limited to the above-described embodiments, and various improvements and modifications can be made without departing from the scope of the present invention.

Description of the symbols

1a, 1b major surface

2 through hole

3 side wall

3a inclined wall surface

10. 10A, 10B, 10C sheet Material for annealing treatment

20. 20a, 20B glass blank

30 layered product

40 heating furnace

50 clamp

60 base

Claims

1. An annealing-treated plate material used for annealing a plate-shaped blank, which is one of 2 or more plate materials laminated so as to sandwich the blank from both sides,

having a pair of major surfaces, at least one of which is in contact with the blank,

the plate member is provided with 1 or 2 or more through holes which are opened in the main surface and penetrate the plate member,

the main surface has an arithmetic mean roughness adjusted to form a gap for air to flow into between the laminated sheet material and the blank,

the through hole is communicated with the gap,

where the blank is set with a circular hole formed,

the through-hole is open in a region of the main surface of the plate material, which is in contact with the portion of the blank where the position is set.

2. The annealing-treated plate material according to claim 1, wherein the sum of the arithmetic mean roughness of the main surface of said plate material and the main surface of said blank in contact with said main surface is 0.2 μm or more.

3. The annealing-treated plate according to claim 1 or 2, wherein an arithmetic mean roughness of a main surface of the plate is larger than an arithmetic mean roughness of a main surface of the ingot which is in contact with the main surface.

4. The annealing-treated plate material according to any one of claims 1 to 3, wherein an arithmetic mean roughness of the main surface of the plate material is 0.2 μm to 1.0 μm.

5. The annealing-treated plate material according to any one of claims 1 to 4, wherein at least one of the through-holes is opened in a main surface of the plate material so that an edge of the plate material surrounding the at least one through-hole abuts on the main surface of the blank.

6. The annealing-treated plate material according to any one of claims 1 to 5, wherein the through-holes that open to the main surface of the plate material have a circular shape,

the diameter of the through hole is 1 mm-6 mm.

7. The annealing treatment plate material according to any one of claims 1 to 6, wherein 2 or more through-holes are provided, and the through-holes are dispersedly opened in a main surface of the plate material.

8. The annealing-treated plate material according to claim 7, wherein when the main surface of said plate material is divided into 2 or more regions having an equal area,

the 2 or more through holes are arranged in the same number in each region.

9. The annealing treatment plate material according to any one of claims 1 to 8, wherein a side wall of the plate material surrounding the through-hole is chamfered so that a sectional area of the through-hole along a direction parallel to a main surface of the plate material increases as approaching the main surface of the plate material.

10. A method for manufacturing a plate material for annealing, the plate material being used for annealing a plate-like blank, the plate material being one of 2 or more plate materials stacked so as to sandwich the blank from both sides,

the manufacturing method comprises a molding treatment for molding the raw material powder of the plate material filled in the mold for molding,

11. A method for manufacturing a substrate, comprising an annealing treatment, wherein at least 2 plate materials of the annealing-treated plate material according to any one of claims 1 to 9 or the annealing-treated plate material manufactured by the manufacturing method according to claim 10 are laminated so as to sandwich a plate-shaped blank material from both sides, and the laminated body is heated to anneal the blank material.