Large-size lithium cobalt oxide ceramic target material and method for manufacturing the same

Abstract

The present application relates to a kind of large size lithium cobaltate ceramic target and its preparation method, the preparation method includes the following steps: (1) mixing binder, dispersing agent, solvent and lithium cobaltate, spray drying, obtain mixed material;(2) mixed material is loaded into mould, and cold isostatic pressing is carried out, and lithium cobaltate green body is obtained;(3) after lithium cobaltate green body is carried out and is debound, again, hot isostatic pressing is carried out, and the large size lithium cobaltate ceramic target is obtained;The size of the ceramic target is long (800mm-1000mm) × wide (300mm-500mm).The present application is prepared by cold isostatic pressing and hot isostatic pressing large size lithium cobaltate ceramic target, and preparation process is simple, high efficiency, low cost, short production cycle, easy to mass production;Preparation obtained large size lithium cobaltate ceramic target, good uniformity and high density.

Description

Technical Field

[0001] This invention relates to the field of lithium cobalt oxide materials technology, to a lithium cobalt oxide ceramic target and its preparation method, and particularly to a large-size lithium cobalt oxide ceramic target and its preparation method. Background Technology

[0002] The advent of batteries has reduced our dependence on non-renewable resources. With the rapid development of the electronics industry, electronic products are becoming smaller, thinner, and more portable, placing new demands on batteries. Lithium-ion solid-state batteries, with their higher energy density, longer cycle life, and higher operating voltage, have attracted considerable attention. Compared to liquid lithium-ion batteries, all-solid-state batteries offer higher safety, greater energy density, and a wider operating temperature range, and have become the latest area of ​​development in lithium-ion battery technology.

[0003] The earliest cathode material for thin-film batteries was TiS2. With the successful development of the high-performance solid-state electrolyte LiPON, lithium cobalt oxide has attracted widespread research as a cathode material for LiPON-type solid-state thin-film batteries. Due to its high voltage, high specific energy density, good cycle performance, and simple fabrication process, lithium cobalt oxide is currently the mainstream cathode material for lithium-ion batteries. With the development of thin-film solid-state batteries, higher requirements are being placed on the lithium cobalt oxide target material for magnetron sputtering of all-solid-state thin-film batteries.

[0004] The lithium cobalt oxide ceramic targets prepared in the existing technology are small in size. Therefore, how to prepare large-size lithium cobalt oxide ceramic targets with good uniformity and high density has become an urgent problem to be solved. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a large-size lithium cobalt oxide ceramic target and its preparation method. The large-size lithium cobalt oxide ceramic target is prepared by cold isostatic pressing and hot isostatic pressing processes. The preparation process is simple, efficient, low-cost, and has a short production cycle, making it easy for mass production. The prepared large-size lithium cobalt oxide ceramic target has good uniformity and high density.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a method for preparing a large-size lithium cobalt oxide ceramic target, the method comprising the following steps: (1) mixing a binder, a dispersant, a solvent and lithium cobalt oxide, spray drying to obtain a mixture; (2) loading the mixture into a mold and performing cold isostatic pressing to obtain a lithium cobalt oxide green body; (3) degreasing the lithium cobalt oxide green body and then performing hot isostatic pressing to obtain the large-size lithium cobalt oxide ceramic target; the size of the ceramic target is length (800mm-1000mm) × width (300mm-500mm).

[0008] This invention prepares large-size lithium cobalt oxide ceramic targets by cold isostatic pressing and hot isostatic pressing. The preparation process is simple, efficient, low-cost, and has a short production cycle, making it easy for mass production. The large-size lithium cobalt oxide ceramic targets prepared have good uniformity and high density.

[0009] Preferably, the adhesive in step (1) comprises polyvinyl alcohol.

[0010] Preferably, the amount of the binder accounts for 2wt%-5wt% of the total amount of binder, dispersant and lithium cobalt oxide, for example, it can be 2wt%, 2.5wt%, 3wt%, 4wt%, 4.5wt% or 5wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0011] This invention further improves the purity and density of the target material by adjusting the amount of binder. Within the preferred range of binder dosage, the prepared lithium cobalt oxide ceramic target material exhibits high purity and high density.

[0012] Preferably, the dispersant comprises any one or a combination of at least two of polyacrylic acid, polyacrylamide, sodium hexametaphosphate, or sodium acrylate. Typical but non-limiting combinations include a combination of polyacrylic acid and polyacrylamide, a combination of sodium hexametaphosphate and sodium acrylate, or a combination of polyacrylamide, sodium hexametaphosphate, and sodium acrylate.

[0013] Preferably, the amount of the dispersant is 0.5wt%-3wt% of the total amount of binder, dispersant and lithium cobalt oxide, for example, it can be 0.5wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt% or 3wt%, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0014] Preferably, the solvent includes water.

[0015] Preferably, the mixing in step (1) includes three stages of mixing.

[0016] Preferably, the mixing stage includes: mixing a solvent and a dispersant to obtain a mixture.

[0017] Preferably, the mixing time is 0.5h-3h, for example, it can be 0.5h, 1h, 1.5h, 2h, 2.5h or 3h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0018] Preferably, the two-stage mixing includes: mixing a primary mixture and lithium cobalt oxide powder in two stages to obtain a two-stage mixture.

[0019] Preferably, the mixing time for the two stages is 6h-24h, for example, it can be 6h, 10h, 14h, 18h, 22h or 24h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] Preferably, the three-stage mixing includes: mixing the two-stage mixture and the binder in three stages to obtain a mixed liquid slurry.

[0021] Preferably, the mixing time for the three segments is 6h-24h, for example, it can be 6h, 10h, 14h, 18h, 22h or 24h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0022] Preferably, after spray drying in step (1), a spherical mixture is obtained.

[0023] Preferably, the particle size D50 of the spherical mixture is 30μm-150μm, for example, it can be 30μm, 50μm, 70μm, 100μm, 120μm or 150μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0024] This invention further improves the purity and density of the target material by further controlling the particle size of the spherical mixture. Within the preferred range of spherical mixture particle size, the prepared lithium cobalt oxide ceramic target material exhibits high purity and high density.

[0025] Preferably, the mold in step (2) includes a rubber mold.

[0026] Preferably, the pressure of the cold isostatic pressing in step (2) is 200MPa-250MPa, for example, it can be 200MPa, 210MPa, 220MPa, 230MPa, 240MPa or 250MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0027] Preferably, the holding time of cold isostatic pressing in step (2) is 10 min to 40 min, for example, it can be 10 min, 20 min, 30 min, 35 min or 40 min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0028] This invention further improves the purity and density of the target material by controlling the pressure and holding time of cold isostatic pressing, while ensuring the integrity of the target material. Within the preferred range of cold isostatic pressing pressure and holding time, the prepared lithium cobalt oxide ceramic target material has high purity and high density, and the integrity and uniformity of the target material can be guaranteed.

[0029] Preferably, the heat preservation temperature for degreasing in step (3) is 500℃-600℃, for example, it can be 500℃, 520℃, 540℃, 560℃, 580℃ or 600℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0030] Preferably, the heat preservation time for degreasing in step (3) is 1h-5h, for example, it can be 1h, 1.5h, 2h, 3h, 4h or 5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0031] This invention further improves the purity of the target material by controlling the degreasing temperature and time. Under optimized degreasing and holding temperatures and times, the purity of the prepared target material is further enhanced.

[0032] Preferably, the degreasing apparatus in step (3) includes a lifting furnace.

[0033] Preferably, the hot isostatic pressing mold in step (3) includes a stainless steel sheath.

[0034] Preferably, the pressure of the hot isostatic pressing in step (3) is 150MPa-200MPa, for example, it can be 150MPa, 160MPa, 170MPa, 180MPa, 190MPa or 200MPa, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0035] Preferably, the sintering temperature of hot isostatic pressing in step (3) is 900℃-1200℃, for example, it can be 900℃, 950℃, 1000℃, 1050℃, 1100℃ or 1200℃, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0036] Preferably, the heat preservation and pressure holding time of the hot isostatic pressing in step (3) is 1h-5h, for example, it can be 1h, 1.5h, 2h, 3h, 4h or 5h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0037] This invention further improves the purity and density of the target material by controlling the sintering temperature and holding time of hot isostatic pressing (HIP), while ensuring the integrity of the target material. Within the preferred range of HIP sintering temperature and holding time, the prepared lithium cobalt oxide ceramic target material has high purity and high density, and the integrity and uniformity of the target material can be guaranteed.

[0038] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0039] (1) Add solvent and dispersant, mix for 0.5h-3h in the first stage; then add lithium cobalt oxide powder, mix for 6h-24h in the second stage; finally add binder, mix for 6h-24h in the third stage to obtain mixed liquid slurry.

[0040] (2) The mixed liquid slurry is passed into a spray granulation equipment for drying to obtain spherical mixture, wherein the particle size D50 of the spherical mixture is 30μm-150μm.

[0041] (3) The spherical mixture is loaded into a mold with a length of (800mm-1000mm) × width of (300mm-500mm), placed in a cold isostatic pressing device, and the pressure is adjusted to 200MPa-250MPa. The pressure is held for 10min-40min to obtain a lithium cobalt oxide green blank.

[0042] (4) Degrease the lithium cobalt oxide green blank at 500℃-600℃ for 1h-5h to obtain the degreased lithium cobalt oxide green blank.

[0043] (5) Place the degreased lithium cobalt oxide green blank into a hot isostatic pressing mold, adjust the pressure to 150MPa-200MPa, the sintering temperature to 900℃-1200℃, and the holding time to 1h-5h to obtain the large-size lithium cobalt oxide ceramic target.

[0044] In a second aspect, the present invention provides a large-size lithium cobalt oxide ceramic target, which is prepared according to the preparation method described in the first aspect.

[0045] Preferably, the length of the lithium cobalt oxide ceramic target is 800mm-1000mm, for example, it can be 800mm, 850mm, 900mm, 950mm or 1000mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0046] Preferably, the width of the lithium cobalt oxide ceramic target is 300mm-500mm, for example, it can be 300mm, 350mm, 400mm, 450mm or 500mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0047] Preferably, the thickness of the lithium cobalt oxide ceramic target is 10mm-20mm, for example, it can be 10mm, 12mm, 14mm, 16mm, 18mm or 20mm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0048] Compared with the prior art, the present invention has at least the following beneficial effects:

[0049] This invention prepares large-size lithium cobalt oxide ceramic targets by cold isostatic pressing and hot isostatic pressing. The preparation process is simple, efficient, low-cost, and has a short production cycle, making it easy for mass production. The large-size lithium cobalt oxide ceramic targets prepared have good uniformity and high density. Detailed Implementation

[0050] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0051] Example 1

[0052] This embodiment provides a method for preparing a large-size lithium cobalt oxide ceramic target, the method comprising the following steps:

[0053] (1) Add 2 parts of polyacrylic acid and 200 parts of water to the mixing tank and mix for 2 hours; then add 95 parts of lithium cobalt oxide powder and mix for 12 hours; finally add 3 parts of polyvinyl alcohol solution and mix for 12 hours to obtain a mixed liquid slurry.

[0054] (2) The mixed liquid slurry was passed into a spray granulation equipment for drying to prepare a spherical mixture with a D50 of 80 μm;

[0055] (3) The spherical mixture is loaded into a rubber mold with a size of 1000mm×500mm and placed in a cold isostatic pressing equipment. The pressure of cold isostatic pressing is 230MPa and the holding pressure of cold isostatic pressing is 30min to obtain lithium cobalt oxide green blank.

[0056] (4) The lithium cobalt oxide green billet is placed in a lifting furnace for degreasing. The degreasing temperature is 550℃ and the degreasing time is 3h to obtain the degreased lithium cobalt oxide green billet.

[0057] (5) The degreased lithium cobalt oxide ceramic green body is placed in a stainless steel sleeve, sealed and welded, and then placed in a hot isostatic pressing (HIP) equipment. The HIP pressure is 180 MPa, the HIP sintering temperature is 1000 °C, and the HIP holding time is 3 h to obtain the large-size lithium cobalt oxide ceramic target.

[0058] Example 2

[0059] This embodiment provides a method for preparing a large-size lithium cobalt oxide ceramic target, the method comprising the following steps:

[0060] (1) Add 0.5 parts of polyacrylic acid and 200 parts of water to the powder mixture and mix for 0.5 hours; then add 97.5 parts of lithium cobalt oxide powder and mix for 6 hours; add 2 parts of polyvinyl alcohol solution and mix for 6 hours to obtain a mixed liquid slurry.

[0061] (2) The mixed liquid slurry was passed into a spray granulation equipment for drying to prepare a spherical mixture with a D50 of 30 μm;

[0062] (3) The spherical mixture is loaded into a rubber mold with a size of 800mm×300mm and placed in a cold isostatic pressing equipment. The pressure of cold isostatic pressing is 200MPa and the holding pressure of cold isostatic pressing is 40min to obtain lithium cobalt oxide green blank.

[0063] (4) The lithium cobalt oxide green billet is placed in a lifting furnace for degreasing. The degreasing temperature is 500℃ and the degreasing time is 5h to obtain the degreased lithium cobalt oxide green billet.

[0064] (5) The degreased lithium cobalt oxide ceramic green body is placed in a stainless steel sleeve, sealed and welded, and then placed in a hot isostatic pressing (HIP) equipment. The HIP pressure is 150 MPa, the HIP sintering temperature is 900 °C, and the HIP holding time is 5 h to obtain the large-size lithium cobalt oxide ceramic target.

[0065] Example 3

[0066] This embodiment provides a method for preparing a large-size lithium cobalt oxide ceramic target, the method comprising the following steps:

[0067] (1) Add 3 parts of polyacrylamide and 200 parts of water to the powder mixture and mix for 3 hours; then add 92 parts of lithium cobalt oxide powder and mix for 24 hours; add 5 parts of polyvinyl alcohol solution and mix for 24 hours to obtain a mixed liquid slurry.

[0068] (2) The mixed liquid slurry was passed into a spray granulation equipment for drying to prepare a spherical mixture with a D50 of 150μm;

[0069] (3) The spherical mixture is loaded into a rubber mold with a size of 800mm×500mm and placed in a cold isostatic pressing equipment. The pressure of the cold isostatic pressing is 250MPa, and the pressure is held for 10min to obtain lithium cobalt oxide green blank.

[0070] (4) The lithium cobalt oxide green billet is placed in a lifting furnace for degreasing. The degreasing temperature is 600℃ and the degreasing time is 1h to obtain the degreased lithium cobalt oxide green billet.

[0071] (5) The degreased lithium cobalt oxide ceramic green body is placed in a stainless steel sleeve, sealed and welded, and then placed in a hot isostatic pressing (HIP) equipment. The HIP pressure is 200 MPa, the HIP sintering temperature is 1200 °C, and the HIP holding time is 1 h to obtain the large-size lithium cobalt oxide ceramic target.

[0072] Example 4

[0073] The only difference between this embodiment and embodiment 1 is that, except that the pressure of cold isostatic pressing in step (3) is 180 MPa, everything else is the same as in embodiment 1.

[0074] Example 5

[0075] The only difference between this embodiment and embodiment 1 is that, except that the holding time for cold isostatic pressing in step (3) is 45 minutes, everything else is the same as in embodiment 1.

[0076] Example 6

[0077] The only difference between this embodiment and embodiment 1 is that, except that the degreasing temperature in step (4) is 450°C, everything else is the same as in embodiment 1.

[0078] Example 7

[0079] The only difference between this embodiment and embodiment 1 is that, except for the degreasing time of step (4) being 0.5 hours, everything else is the same as in embodiment 1.

[0080] Example 8

[0081] The only difference between this embodiment and embodiment 1 is that, except that the pressure of hot isostatic pressing in step (3) is 130 MPa, everything else is the same as in embodiment 1.

[0082] Example 9

[0083] The only difference between this embodiment and embodiment 1 is that, except that the sintering temperature of hot isostatic pressing in step (3) is 850°C, everything else is the same as in embodiment 1.

[0084] Example 10

[0085] The only difference between this embodiment and embodiment 1 is that, except that the heat preservation time of hot isostatic pressing in step (3) is 0.5h, everything else is the same as in embodiment 1.

[0086] Comparative Example 1

[0087] The only difference between this comparative example and Example 1 is that, except for step (3) not being performed, everything else is the same as in Example 1.

[0088] Comparative Example 2

[0089] The only difference between this comparative example and Example 1 is that, except that in step (5) the sample is not placed in a hot isostatic pressing apparatus and is sintered directly at 1000°C for 3 hours, the rest is the same as in Example 1.

[0090] Test methods

[0091] The lithium cobalt oxide ceramic targets prepared in Examples 1-10 and Comparative Examples 1-2 were subjected to density testing. The density of the lithium cobalt oxide ceramic targets was tested using an AKD-220A density instrument from Yangzhou Aike Ruide Instrument Co., Ltd. The test method was the water displacement method, and the test results were recorded in Table 1.

[0092] Table 1

[0093] Example 1 98％ Example 2 96.2％ Example 3 93.5％ Example 4 90.8％ Example 5 97.2％ Example 6 94.3％ Example 7 88％ Example 8 86.3％ Example 9 93.7％ Example 10 91.45％ Comparative Example 1 63％ Comparative Example 2 83％

[0094] The test results show that:

[0095] (1) As can be seen from Examples 1-10 and Comparative Examples 1-2, the present invention prepares large-size lithium cobalt oxide ceramic targets through cold isostatic pressing and hot isostatic pressing processes. The preparation process is simple, efficient, low-cost, and has a short production cycle, making it easy to mass-produce. The large-size lithium cobalt oxide ceramic targets prepared have good uniformity and high density.

[0096] (2) As can be seen from Examples 1 and 4-5, the large-size lithium cobalt oxide ceramic target prepared by the present invention by further controlling the pressure and holding time of cold isobaric pressure has a higher density.

[0097] (3) As can be seen from Examples 1 and 6-7, the large-size lithium cobalt oxide ceramic target prepared by the present invention by further controlling the temperature and time of degreasing has a higher density.

[0098] (4) As can be seen from Examples 1 and 8-10, the large-size lithium cobalt oxide ceramic target prepared by the present invention by further controlling the pressure of thermal isobaric stress, sintering temperature and holding time has a higher density.

[0099] In summary, this invention prepares large-size lithium cobalt oxide ceramic targets through cold isostatic pressing and hot isostatic pressing processes. The preparation process is simple, efficient, low-cost, and has a short production cycle, making it easy for mass production. The prepared large-size lithium cobalt oxide ceramic targets have good uniformity and high density.

[0100] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a large-size lithium cobalt oxide ceramic target, characterized in that, The preparation method includes the following steps: (1) Mix the binder, dispersant, solvent and lithium cobalt oxide, and spray dry to obtain a mixture; the amount of the binder is 2wt%-5wt% of the total amount of binder, dispersant and lithium cobalt oxide; The adhesive mentioned in step (1) is polyvinyl alcohol; (2) Load the mixture into the mold, adjust the pressure to 200MPa-250MPa, perform cold isostatic pressing, hold the pressure for 10min-40min, and obtain lithium cobalt oxide green blank; (3) After degreasing the lithium cobalt oxide green blank at 500℃-600℃, it is then subjected to hot isostatic pressing to obtain the large-size lithium cobalt oxide ceramic target. The defatting and heat preservation time is 1-5 hours; The pressure of the hot isostatic pressing is 150MPa-200MPa; The sintering temperature of the hot isostatic pressing is 900℃-1200℃; The heat preservation and pressure holding time for the hot isostatic pressing is 1h-5h; The ceramic target material has dimensions of length (800mm-1000mm) × width (300mm-500mm).

2. The preparation method according to claim 1, characterized in that, The dispersant includes any one or a combination of at least two of polyacrylic acid, polyacrylamide, sodium hexametaphosphate, or sodium acrylate.

3. The preparation method according to claim 1, characterized in that, The amount of the dispersant is 0.5wt%-3wt% of the total amount of binder, dispersant and lithium cobalt oxide.

4. The preparation method according to claim 1, characterized in that, The solvent includes water.

5. The preparation method according to claim 1, characterized in that, The mixing in step (1) includes three stages of mixing, namely the first stage of mixing, the second stage of mixing, and the third stage of mixing.

6. The preparation method according to claim 5, characterized in that, The first mixing stage includes: mixing solvent and dispersant to obtain a mixture.

7. The preparation method according to claim 6, characterized in that, The mixing time for the first stage is 0.5h-3h.

8. The preparation method according to claim 5, characterized in that, The second stage of mixing includes: mixing the first stage mixture and lithium cobalt oxide powder in a second stage to obtain a second stage mixture.

9. The preparation method according to claim 8, characterized in that, The mixing time for the second stage is 6h-24h.

10. The preparation method according to claim 5, characterized in that, The third stage of mixing includes: mixing the second stage mixture and the binder in three stages to obtain a mixed liquid slurry.

11. The preparation method according to claim 10, characterized in that, The mixing time for the third stage is 6h-24h.

12. The preparation method according to claim 1, characterized in that, After spray drying in step (1), a spherical mixture is obtained.

13. The preparation method according to claim 12, characterized in that, The particle size D50 of the spherical mixture is 30μm-150μm.

14. The preparation method according to claim 1, characterized in that, The mold in step (2) includes a rubber mold.

15. The preparation method according to claim 1, characterized in that, The hot isostatic pressing mold in step (3) includes a stainless steel sheath.

16. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: (1) Add solvent and dispersant, mix for 0.5h-3h in the first stage; then add lithium cobalt oxide powder, mix for 6h-24h in the second stage; finally add binder, mix for 6h-24h in the third stage to obtain a mixed liquid slurry; (2) The mixed liquid slurry is passed into a spray granulation equipment for drying to obtain spherical mixture; (3) The spherical mixture is loaded into a mold with a length of (800mm-1000mm) × width of (300mm-500mm), placed in a cold isostatic pressing equipment, and the pressure is adjusted to 200MPa-250MPa. The pressure is held for 10min-40min to obtain lithium cobalt oxide green blank. (4) Degrease the lithium cobalt oxide green blank at 500℃-600℃ for 1h-5h to obtain the degreased lithium cobalt oxide green blank; (5) Place the degreased lithium cobalt oxide green blank into a hot isostatic pressing mold, adjust the pressure to 150MPa-200MPa, the sintering temperature to 900℃-1200℃, and the holding time to 1h-5h to obtain the large-size lithium cobalt oxide ceramic target.

17. A large-size lithium cobalt oxide ceramic target, characterized in that, The lithium cobalt oxide ceramic target is prepared by the preparation method according to any one of claims 1-16.

18. The lithium cobalt oxide ceramic target according to claim 17, characterized in that, The length of the lithium cobalt oxide ceramic target is 800mm-1000mm.

19. The lithium cobalt oxide ceramic target according to claim 18, wherein the width of the lithium cobalt oxide ceramic target is 300mm-500mm.