JP4656194B2 - How to use memory disc scrap material - Google Patents

Description

  The present invention relates to a method for using a scrap material of a memory disk used as a recording medium such as a hard disk, and an Al—Si based aluminum alloy primary crystal Si refining material using the memory disk.

  A memory disk is a magnetic recording medium mounted on a hard disk or the like. The size varies depending on the equipment to be mounted, but in many cases, it has a thin donut shape with a large surface area. The surface is coated with a magnetic material, and data is recorded by magnetizing the magnetic material. If the memory disk substrate is magnetic, it may adversely affect recording. Therefore, non-magnetic Ni-P plating is applied as a base treatment for applying the magnetic material.

  The dimensional accuracy required for the memory disk, particularly the smoothness of the surface, is extremely strict. Therefore, some inspections after Ni-P plating fail. In addition, products equipped with hard disks become scraps, and memory disks come out as scraps (waste). Conventionally, they are sometimes processed as mere ingots for melting, but on the other hand, there are many Al alloys that do not like the mixing of Ni-P components, and in this case, they are often discarded as scrap. Existed.

  In recent years, with the rapid increase in storage devices, the dimensional accuracy required for memory disks has become extremely severe, and the number of products that fail inspection has increased. In addition, various products have built-in computers, the demand for hard disks has increased dramatically, the demand for memory disks has also increased, and therefore the number of memory disks that come from scraps of hard disks has also increased. They have conventionally been discarded as scrap or simply processed as melting ingots.

  However, when discarded as scrap, it is necessary that the stored information be completely erased, and discarding as scrap is not preferable from an environmental point of view. On the other hand, when processing as a simple melting ingot, components used as plating may become a problem as impurities, and purification may be required.

  In addition, the recovered memory disk scrap material includes memory disks with various undercoats, magnetic films, protective films, lubricating films, etc. (including finished memory disks). Therefore, if this is directly charged into the molten aluminum alloy in the melting furnace, various coating layers will be present in the molten metal as coatings and inclusions (oxides, carbides, etc.). Depending on the sedation time after charging, There was a risk of degrading the quality of the ingot or cast product as the final product.

  Accordingly, an object of the present invention is to provide a more effective method of using the scrap material of the memory disk.

The present invention provides a method of using a scrap material of an aluminum alloy memory disk having Ni-P plating on its surface, and using the scrap material as a primary crystal Si refining material in the production of an Al-Si based aluminum alloy. To do.
The present invention also provides an Al—Si based aluminum alloy primary crystal Si refinement material comprising an aluminum alloy memory disk having Ni—P plating on the surface.

  Al—Si-based aluminum alloys are widely used for the purpose of obtaining a cast body having a complicated shape because of excellent castability. In particular, a hypereutectic Al—Si alloy containing 11.7% or more by mass% has low thermal expansion and excellent heat resistance, and the primary crystal is crystallized when the melt is solidified. This primary Si is widely used for sliding members such as pistons because of its high hardness and excellent wear resistance. By the way, if the particle diameter of the primary crystal Si is coarse, it becomes a starting point of fracture, and mechanical properties and machinability are lowered. For this reason, the refinement of primary Si has been carried out by rapidly solidifying the melt during casting or by adding P as a crystallization nucleus of primary Si into the melt. As a method for adding P, a method using a flux such as sodium hexametaphosphate (Japanese Patent Laid-Open No. 52-153817), a method of adding a phosphorus-containing alloy such as Cu-8% P (Japanese Patent Laid-Open No. 60-204843) Further, a method of adding a P-containing alloy plated surface of an aluminum alloy (Japanese Patent Laid-Open No. 3-207828) is known.

  As a result of various studies on the effective utilization method of the scrap material of the memory disk, the present inventors have found that an aluminum alloy memory disk whose surface is Ni-P plated is an Al-Si based aluminum alloy. It has been found that it is effective as a material for refining primary Si. In other words, the primary crystal Si refinement material of the present invention, in an Al-Si-based aluminum alloy, crystallizes coarse primary crystal that reduces mechanical properties and machinability by miniaturizing primary crystal Si. There is an effect to prevent. The method of use of the present invention is also effective as a method for reusing (recycling) scrap material of an aluminum alloy memory disk that has been subjected to Ni-P plating.

  As a result of various studies on the effective use of the scrap material of the memory disk, the present inventors have reached the present invention that effectively uses the plating component of the memory disk, which has been conventionally regarded as an impurity, on the contrary. It was. In an aluminum alloy memory disk with Ni-P plating on the surface, since the plating component P exists in a solid solution state, if these are dissolved in the molten aluminum alloy, the P and Al The reaction is carried out promptly, and a large amount of Al—P compound serving as a crystal nucleus of primary Si is produced. Unlike the flux method or the method of adding a phosphorus (P) -containing alloy, the method using a Ni-P plated alloy as the primary crystal Si refiner does not require decomposition of the intermetallic compound of P. The temperature can also be lowered, which is advantageous in terms of low gas absorption and P yield.

  Since the composition of the primary crystal Si refined material of the present invention is stable compared to the case where alloy scraps plated with P-containing alloy are used as the primary crystal Si refined material, the content of P and other components It has the advantage that it is easy to control. In addition, if the memory disk has a normal thin donut shape, it has a large surface area per weight, so it can be quickly dissolved in the molten aluminum alloy, and the holding time can be shortened. It has the advantage of being finished. In addition, it is transported because of its thinness (can be stacked and stored), donut shape (can use the central hole), and versatility of shape (can use various existing methods, equipment, and equipment such as shrink packing) It is also easy to handle when charging into molten metal. Furthermore, compared with the case of producing a primary crystal Si refined material by newly performing P-containing alloy plating on an aluminum alloy, what is supposed to be scrap can be used effectively as it is, which has a great advantage in terms of manufacturing cost. .

  In addition, the method of use of the present invention has an excellent advantage as a method for processing a scrap material of a memory disk. That is, after a used memory disk is used in the method of use of the present invention, information recorded on the memory disk is completely lost, which is advantageous in protecting confidential information such as personal information. . In addition, unlike the case of simply using an ingot for casting, there is no need to consider the plating component as an impurity, so there is an advantage in terms of the processing cost of the scrap material of the memory disk.

[Memory disk]
A memory disk is a magnetic recording medium mounted on a hard disk or the like. The size varies depending on the equipment to be mounted, but in many cases, it has a thin donut shape with a large surface area. In the memory disk used in the present invention, for example, a blank disk made of an aluminum alloy is subjected to Ni-P plating to produce a memory disk substrate (substrate). Further, a fine surface is formed on the surface of the memory disk substrate. It is manufactured through a texture process for forming irregularities, a cleaning process, a sputtering process for depositing a base layer and various films, a burnishing process for removing and polishing surface protrusions, and a louver process for forming a lubricating film. Thereafter, it is inspected in a test process (glide height test process, certify test process, etc.) to be completed as a final product.

  In this specification, the term “memory disk” refers to a finished memory disk having a coating layer, a memory disk substrate that has not been subjected to any of the above-described processes, or a coating layer (underlayer, magnetic film, protective layer). All memory disk substrates that do not have or partially have a film, a lubricating film, etc. are also included. Further, in this specification, “Ni—P plating is applied to the surface” means “Ni—P plating is applied to the surface of the blank material or the memory disk substrate”. Including those with other coatings on the P-plating.

  Defective or unnecessary memory disk substrate produced in each manufacturing process (especially test process), defective or unnecessary memory disk substrate after completion, or discarded (after magnetic information is recorded) The memory disk is generally referred to as “memory disk scrap”. This “memory disk scrap” includes both crushed and doughnut-shaped scraps. The scrap material after Ni-P plating can be used as "aluminum alloy memory disk (surface scrap material) having Ni-P plating on its surface" of the present invention.

  The composition of the Ni-P plating applied to the surface of the memory disk used in the present invention is not particularly limited, but the amount of P added is larger when the P content is larger and the plating layer is thicker. This is preferable because it requires less.

  In addition, memory disks with various underlayers, magnetic films, protective films, lubricating films, and other coatings (including finished memory disks) can be used in the present invention as they are. These layers can be removed by a treatment such as sand blasting when it is not desired to add impurities to the Al—Si based aluminum alloy. In addition, as long as the Ni-P plating portion is not lost, it can be used after various physical processing such as cutting.

Embodiment
Hereinafter, embodiments of the present invention will be described, but these are not intended to limit the present invention, but are disclosed for the purpose of illustration. The technical scope of the present invention is defined by the description of the claims, and those skilled in the art can make various design changes within the technical scope of the invention described in the claims.

  In the first embodiment of the present invention, in the method of using a scrap material of an aluminum alloy memory disk whose surface is Ni-P plated, in the production of an Al-Si based aluminum alloy, the refinement of primary Si is refined. It is a method used as a material.

The utilization method of this invention can be performed in the following procedures, for example.
1) In the step of making an ingot of an Al—Si based aluminum alloy, the molten aluminum alloy is adjusted. Alternatively, an aluminum alloy memory disk whose surface is plated with Ni—P is introduced for the purpose of containing a P component in advance.
2) An Al—Si based aluminum alloy ingot or a molten Al—Si based aluminum alloy in which the P component is previously dissolved in the ingot is prepared.
3) In the melt of Al-Si based aluminum alloy or in the melt containing P component in advance, if this is less than the control concentration value suitable for casting, as a supplementary primary Si refinement material, An aluminum alloy memory disk with Ni-P plating on the surface is inserted.
4) Hold until P in plating is dissolved in molten alloy.
5) The molten Al-Si-based aluminum alloy after holding is poured into a mold or the like to perform casting.
For example, 680 to 850 ° C. is used as the temperature of the molten alloy when the memory disk is introduced as the primary Si refinement material, and this is appropriately adjusted according to the composition of the Al—Si aluminum alloy. . Further, the subsequent holding temperature and holding time are also appropriately adjusted depending on the composition of the Al—Si-based aluminum alloy and the amount of P to be added. For example, the holding temperature and holding time are held at 680 to 850 ° C. for about 10 to 180 minutes. As for the amount of the memory disk to be added as the primary Si refinement material, so as to achieve the P amount (for example, 0.001 to 0.03%) that is usually used for refinement in the technical field, In consideration of the composition, thickness, surface area, and P yield of Ni—P plating, it is used after adjusting as appropriate.

  A second embodiment of the present invention is an Al—Si based aluminum alloy primary crystal Si refinement material comprising an aluminum alloy memory disk having Ni—P plating on the surface.

  The primary crystal Si refining material of the present invention is characterized by comprising a memory disk made of an aluminum alloy having Ni-P plating on its surface. This primary crystal Si refining material is put into a molten Al-Si aluminum alloy for manufacturing purposes. Thereafter, the molten alloy is held until P in the Ni—P plating is dissolved in the molten alloy, and the target Al—Si based aluminum alloy is manufactured by casting into a mold. For example, 680 to 850 ° C. is used as the temperature of the molten alloy when the primary Si refinement material of the present invention is charged, and this is appropriately adjusted according to the composition of the Al—Si based aluminum alloy molten metal. The In addition, the holding time and holding temperature are also appropriately adjusted depending on the composition of the Al—Si-based aluminum alloy molten metal and the amount of P to be added. For example, the holding time and holding temperature are held at 680 to 850 ° C. for about 10 to 180 minutes. With respect to the amount of the disk added as the primary Si refinement material, Ni is used so as to achieve a P amount (for example, 0.001 to 0.03%) that is usually used for refinement in the technical field. -It is used after adjusting appropriately in consideration of the composition, thickness, surface area and P yield of P plating.

  In addition, the primary crystal Si refinement material of the present invention should be used after physical processing such as breaking, crushing, cutting or bending folding is performed on the memory disk as long as the Ni-P plated portion is not lost. You can also. By processing into an appropriate shape and size, effects such as fine adjustment of the amount, convenience of transportation, and improvement of dissolution rate can be obtained. Further, in the case of a memory disk substrate with various coatings, a finished memory disk, or a used memory disk, a sand blasting process may be performed to remove the coating layer.

  In the third embodiment of the present invention, in the method for producing a primary Si refined material of an Al-Si-based aluminum alloy, the scrap material of an aluminum alloy memory disk whose surface is Ni-P plated is recovered. It is a manufacturing method including the process to do.

  In the manufacturing method of the present invention, the scrap material recovered in the process of recovering the scrap material of the aluminum alloy memory disk having Ni-P plating on the surface is used as it is for the primary crystal Si of the Al-Si based aluminum alloy. It can be used as a fine material. In the manufacturing method of the present invention, the presence or absence of Ni-P plating or whether it is made of an aluminum alloy may be judged from the manufacturing process, model number, etc., but the presence or absence of Ni-P plating applied to the memory disk is inspected. And a step of inspecting whether or not the memory disk is made of an aluminum alloy. These inspections can be performed by using, for example, an emission analysis method or a fluorescent X-ray analysis method. Further, when taking out a used memory disk from a memory disk built-in device such as a hard disk, a step of taking out the memory disk from the memory disk built-in device may be further included. In addition, when it is desired to remove the coating layer, a step of removing the coating layer from the memory disk substrate may be further included. These removing steps are performed by, for example, sand blasting. In addition, when it is desired to use a memory disk that has been subjected to physical processing such as breaking, crushing, cutting, or bending, it may further include a step of breaking, crushing, cutting, bending, or bending the memory disk.

  In a fourth embodiment of the present invention, a scrap material of an aluminum alloy memory disk whose surface is Ni-P plated is used as a primary Si refinement material in an Al-Si based aluminum alloy. This is a utilization method including a step of putting a scrap material of a memory disk into an aluminum alloy molten metal in a melting furnace, and a molten metal processing step of adding a flux to perform degassing.

  The recovered memory disk scrap material includes memory disks with various undercoats, magnetic films, protective films, lubricating films, etc. (including finished memory disks). If this is put directly into the molten aluminum alloy in the melting furnace, various coating layers will be present in the molten metal as coatings and inclusions (oxides, carbides, etc.). There is a risk of degrading the quality of the ingot or cast product.

  Therefore, after the recovered scrap material of the memory disk is put into the molten aluminum alloy in the melting furnace, flux is added to remove the coating and inclusions (oxides, carbides, etc.) present in the molten metal as soot. Then, it is desirable to perform a molten metal treatment for dewaxing.

The flux used should just be a thing of the component employ | adopted as a flux for denitrification. Specifically, for example, KAlF ₃ , AlF ₃ , NaF, K ₂ SiF ₆ , which mainly contains a chloride flux such as KCl, NaCl, MgCl _{2 and the} like having a denitrifying effect and further increases the reactivity with molten aluminum. In general, those containing a fluoride-based flux such as the above as an auxiliary component are used. Further, as the heating _agent, K ₂ SO 4, _Na sulfides such as 2 SO _4, is also used those obtained by blending a small amount of carbonate such as Na ₂ CO _3, CaCO 3.

As a method of adding flux to the molten aluminum alloy in the melting furnace, charging and spraying are generally used. When the melting furnace also serves as a small holding furnace such as a crucible furnace, a predetermined amount of flux is added to aluminum. A method of wrapping in foil and pushing it into the molten metal with a phosphorizer is also effective. Further, in the case of a medium- or large-sized melting furnace having a metal holding amount of several tons or more, a method of supplying and spraying the molten metal into the molten metal through a lance together with an inert gas (N ₂ , Ar) is preferable. Recently, a method of supplying and spraying molten metal through a rotating rotor together with an inert gas from a flux feeder has also been adopted. The inert gas is supplied into the molten metal together with the flux, and serves as a medium for so-called degassing treatment that reduces the amount of hydrogen gas in the molten aluminum alloy, so that the dew point is controlled. (For example, a dew point of −60 ° C. or lower) is desirable.

The melt temperature when adding flux to the aluminum alloy melt, the so-called addition temperature,
740-880 degreeC is preferable. When the addition temperature is less than 740 ° C., although depending on the components of the flux, the flux and the molten metal do not sufficiently react, so that the defatting effect is not sufficiently exhibited. When the addition temperature exceeds 880 ° C., there is a risk of accelerating the deterioration of the refractory material in the furnace and shortening the life of the melting furnace. A more preferable addition temperature is 760 to 840 ° C.

  The amount of flux added is preferably 0.05 to 0.30 mass% with respect to the mass of the molten aluminum alloy in the melting furnace. When the amount is less than 0.05% by mass, the effect is not sufficient. When the amount exceeds 0.30% by mass, the degassing effect is sufficient, but the amount of harmful gas generated is increased, and the refractory material in the furnace is further increased. There is a risk of accelerating deterioration and shortening the life of the melting furnace. In consideration of the environment, the amount of flux added is more preferably 0.05 to 0.10% by mass.

  In order to sufficiently react the flux and the molten metal after the flux is added, it is desirable to stir the molten metal with a stirring jig. Generally, after stirring, so-called sedation is performed in which the molten metal is gently held. The sedation time is usually about 30 to 120 minutes, although it depends on the type and capacity of the melting furnace, the amount of molten aluminum alloy in the melting furnace, and the line configuration.

  By this sedation, chloride particles, which are the main components of the flux dispersed in the molten metal, capture the film and inclusions (oxides, carbides, etc.) and float on the surface of the molten metal. Float and separate. The surfaced soot usually contains a certain amount of metal, but the fluoride as a subcomponent of the flux has an effect of promoting the separation of the soot and the metal and generating a smooth so-called dry soot. Finally, the jig floating on the surface of the molten metal is scraped out of the furnace and collected in a scrap can.

  As described above, the ingot which is the final product in the method of using the scrap material of the aluminum alloy memory disk whose surface is subjected to Ni-P plating by performing the molten metal treatment for adding the flux and performing dewaxing. Alternatively, the quality of the cast product can be improved.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.
This example was performed according to the following procedure.
1) A molten alloy of 20 kg of 760 ° C. made of 80% Al, 15% Si, and 3% Cu was prepared by external heating using a graphite crucible.
2) 240g (0.007% P) of each memory disk scrap (doughnut-shaped product (with coating layer), crushed product (with coating layer), donut-shaped product (without coating layer)) for this molten alloy The amount of P dissolved in the alloy was examined by emission analysis, and the dissolution characteristics were examined. (Graph shown by solid line in Fig. 1)
3) Next, the molten alloy before / after each memory disk was solidified at a mold temperature of 150 ° C. using a φ18 × L15 mold as a mold, cut and polished at the center in the length direction, The average crystal grain size of Si was analyzed by image analysis. (Graph shown by broken line in FIG. 1) In the image analysis, the area of primary Si was obtained using a microscope or the like, the diameter of a circle having the same area was calculated and analyzed as the primary Si average particle diameter. .

  The results of the above examples are shown in the graph of FIG. The solid line in FIG. 1 indicates the amount of P dissolved, and the broken line indicates the primary crystal Si average particle diameter.

  As a result of the investigation of solubility characteristics, it was confirmed that when memory disk scrap was used, P quickly dissolved in the aluminum alloy melt not only in the crushed product but also in the donut shape product. In addition to the Ni-P plating layer, it was confirmed that P was rapidly dissolved in a disk having a coating layer as well as in the case without a coating layer. Further, in any case, the yield of P was good.

  Further, regarding the average primary crystal grain size, the average crystal grain size was confirmed to be refined in the case where the memory disk was added to the average primary crystal Si grain size of about 20 μm when the memory disk was not added. This effect was confirmed regardless of the presence or absence of the coating layer in either the doughnut-shaped product or the crushed product.

  From the results of the above examples, memory disk scrap (crushed product / doughnut-shaped product, with / without coating layer) is effective as a primary Si refinement material in the production of Al-Si aluminum alloys. It was confirmed that there was.

It is a graph which shows the melt | dissolution characteristic and refinement | miniaturization characteristic of a memory disk (MD) scrap material.

Claims (4)

  A method of using an aluminum alloy memory disk scrap material having Ni-P plating on the surface thereof, which is used as a primary Si refinement material in the production of an Al-Si based aluminum alloy.   An Al—Si-based aluminum alloy primary crystal Si refinement material comprising an aluminum alloy memory disk having Ni—P plating on the surface.   A method for producing an Al—Si based aluminum alloy primary crystal Si refined material, comprising a step of recovering a scrap material of an aluminum alloy memory disk having a Ni—P plating surface.   The method according to claim 1, comprising a step of putting a scrap material of a memory disk into an aluminum alloy molten metal in a melting furnace, and a molten metal processing step of adding a flux to perform dewaxing.

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