JPH06335866A - Vitrified grinding wheel and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the grinding ratio and grinding quantity by specifying the thickness of the reaction layer in the interface of an abrasive grain and a vitrified joining agent. CONSTITUTION:The thickness of the reaction layer on the interfaces A of the abrasive grains formed in baking and a vitrified joining agent is set to 10mum or less from the surface layer of the abrasive grain to the inside. If the thickness of the reaction layer 15 set to 10mum or more, the denaturation degree of the surface layer of the sintered alumina abrasive grain becomes large, and the grinding wheel faculty is deteriorated. Further, the reaction layer is necessarily to be formed in order to apply the strength as grinding wheel, and the thickness of the reaction layer of 0mum is to be excluded. Further, a vitrified grinding wheel is formed by baking the abrasive grains containing the sintered alumina abrasive grains manufactured by the sol-gel method in at least 5wt.% and the vitrified joining agent at a prescribed temperature. When the abrasive grain is contained in 5wt.% or less, the faculty of the sintered alumina abrasive grain obtained through the sol-gel method can not be hardly developed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vitrified grindstone containing sintered aluminous abrasive grains produced by a sol-gel method and a method for producing the same.

[0002]

2. Description of the Related Art Generally, a vitrified grindstone using sintered alumina produced by a sol-gel method as abrasive grains has a higher grindstone performance than a grindstone using conventional fused alumina abrasive grains. It is known to be excellent.

For example, US Pat. No. 4,543,107 discloses a vitrified grindstone using sintered alumina abrasive grains produced by a sol-gel method and a vitrified bond.
And No. 4,898,597.

In US Pat. No. 4,543,107, when the viscosity and / or aging temperature of the binder is properly controlled, that is, the binder is aged below 1100 ° C. for a normal binder and below 1220 ° C. for a high viscosity binder. It is disclosed that the excellent properties of the sintered alumina abrasive grains are exhibited when the temperature is lowered.

Further, in US Pat. No. 4,898,597,
In order to essentially or drastically reduce the reduction in grinding performance when using a vitrified sintered alumina grinding wheel with an aqueous coolant, it is pre-fired prior to its use as a frit (i.e. as a binder) as a binding medium. Glassy binder compositions) are used.

However, when the sintered alumina abrasive grains produced by the sol-gel method are used as the vitrified grindstone as described above, the crystal grain size is finer and more active than the conventional fused alumina, so that the particles are bonded during firing. The agent is easily affected by the vitrified binder, and it is considered that the grinding wheel performance is deteriorated by the reaction with the vitrified binder at the conventionally used firing temperature.

However, in addition to the above-mentioned US patent, the relationship between the degree of alteration of the sintered alumina-based abrasive grains produced by the sol-gel method and the reaction of the vitrified bond with the vitrified binder and the performance of the grindstone was investigated. There was nothing that was unknown, and it was unknown.

In view of the above circumstances, the present invention has a completely different viewpoint from the prior art, namely, the degree of reactivity between the sintered alumina-based abrasive particles produced by the sol-gel method and the vitrified binder and the deterioration of the grinding performance. It was made from the viewpoint of the presence or absence, the purpose is to control the thickness of the reaction layer of the sintered alumina abrasive grains and the vitrified binder, by vitrified grindstone that does not deteriorate the grindstone performance Another object of the present invention is to provide a composition of a vitrified binder suitable for sintered alumina abrasive grains produced by the sol-gel method, and a method for producing a vitrified grindstone using the binder.

[0009]

Means for Solving the Problems In view of this viewpoint, the present inventor has conducted earnest research from the following points.

(1) In order to evaluate the reactivity between the sintered aluminous abrasive grains produced by the sol-gel method and the vitrified binder, a modified oxide mainly acting as a flux in the glass component of the vitrified binder. The alkali metal oxides (Na ₂ O, Li ₂ O, K ₂ O, etc.) and alkaline earth metal oxides (CaO, MgO, BaO, etc.) corrode from the surface of the sintered alumina abrasive grains. , The hardness of the surface layer of the part that penetrates into the center of the abrasive grain (this is called the reaction layer between the abrasive grain and the vitrified binder) is measured, and the hardness is greater than the hardness of the center of the abrasive grain. It was measured whether there was a decrease in

(2) Further, from the surface layer of the abrasive grains, modifying oxides (Na ₂ O, Li ₂ O, K ₂ O, C) in the vitrified binder are used.
The depth of penetration of aO, MgO) into the abrasive grains was measured by an electronic microanalyzer (E.P.M.A.).

(3) As a result of studying the relationship between the measurement results of (1) and (2) above, the grinding stone strength of the vitrified grindstone, and the grindstone performance, it was found that the reaction layer of the vitrified binder and the bonded aluminous abrasive grains was formed. It has been found that by controlling the thickness to a predetermined value or less, it is possible to obtain a grindstone strength that can be used as a vitrified grindstone and the grindstone performance does not deteriorate.

(4) Based on the above (3), the production system including the preferable composition of the vitrified binder and the firing temperature was determined.

(5) The sintered alumina-based abrasive grains produced by the sol-gel method which are preferable for use in the present invention are the sintered alumina-based abrasive grains of US Pat. Nos. 4,744,802 and 4881951.

The present invention is based on the above (1) to (5).

That is, the vitrified grindstone of the present invention is a vitrified grindstone obtained by firing abrasive particles containing at least 5% by weight or more of sintered alumina abrasive particles produced by the sol-gel method and a vitrified bond at a predetermined temperature. The thickness of the reaction layer at the interface between the abrasive grains and the vitrified bond formed during firing is less than 10 μm from the surface layer of the abrasive grains to the inside thereof (claim 1).

The thickness of the reaction layer is set to less than 10 μm, as shown in the experimental examples described later, when the thickness of the reaction layer is 10 μm or more, the degree of alteration of the surface layer of the sintered alumina abrasive grains is high. This is because the grinding wheel performance is large and deteriorates.

The above reaction layer must be formed in order to impart strength as a grindstone, so 0 μm is excluded.

The reason why at least 5% by weight or more of the sintered alumina abrasive grains produced by the sol-gel method is included is that if the amount is less than 5% by weight, the effect of the sintered alumina-based abrasive grains produced by the sol gel method is hardly exhibited.

The sintered alumina abrasive grains may be abrasive grains made of aluminum oxide containing a rare earth metal for improving the characteristics (claim 2).

The alumina crystal grain size after firing is preferably submicron, and more preferably in the range of 0.05 to 0.8 μm (claim 3).

If it is less than 0.05 μm, the degree of sintering of α-alumina does not proceed so that effective hardness as abrasive grains cannot be obtained. On the other hand, if it exceeds 0.8 μm, the bonding force between α-alumina crystals is weakened. This is because intergranular fracture between crystals often occurs, and the fine crushing mechanism of abrasive grains does not work.

Further, the total amount of the modified oxide contained in the vitrified binder is preferably 20 wt% or less in total (claim 4).

Here, the modified oxide is Na ₂ O, K.
Alkali metal oxides such as ₂ O and Li ₂ O, CaO and Mg
It refers to alkaline earth metal oxides such as O and BaO, and is a component mainly acting as a flux in the binder. The total amount of the modified oxides is set to 20 wt% or less. When the amount of the modified oxide exceeds 20 wt%, the reaction layer at the interface between the abrasive grains and the vitrified binder is baked at the time of firing even if the stone is fired at a low temperature of about 900 to 1100 ° C. This is because the thickness increases and exceeds 10 μm, and the deterioration of the grindstone characteristics becomes remarkable. Further, among the above-mentioned modified oxides, Na ₂ O particularly easily penetrates into the inside of the abrasive grains and causes deterioration of characteristics. Therefore, the amount of Na ₂ O is preferably 10 wt% or less.

The above-mentioned vitrified grindstone is composed of 1200 particles of a vitrified binder and abrasive particles containing at least 5% by weight or more of sintered alumina abrasive particles produced by the sol-gel method.
It is produced by firing at a firing temperature of ℃ or less (Claim 5), and the sintered alumina abrasive grains may be abrasive grains made of aluminum oxide containing a rare earth metal, and α-alumina seeds. And / or a sol containing a rare earth metal is preferably produced by drying and then heat-treating (claim 6), and the amount of the modified oxide contained in the vitrified binder is a total amount. It is desirable that the content is 15 wt% or less (Claim 7).

The above firing temperature is set to 1200 ° C. or lower because when the temperature exceeds 1200 ° C., the abrasive grains cause crystal growth, which causes alteration of the abrasive grains.

The thickness of the reaction layer of the vitrified bond and the crystalline aluminous abrasive grains is determined by the penetration of the composition components in the vitrified bond, particularly the metal elements of the modified oxide, from the surface of the grain into the inside of the grain. It can be represented by the largest value of the distance (depth).

[0028]

[Experimental Example 1] Generally, sintered abrasive grains produced by the sol-gel method are sintered at a lower temperature than conventional fused alumina abrasives that are fired at a maximum of 1300 to 1400 ° C. It is considered that the influence of heat is greater than that of the alumina abrasive grains.

Therefore, first, as a preliminary preparation for producing a vitrified grindstone, the alteration of the abrasive grains in the sintered alumina abrasive grains produced by the sol-gel method depending on the firing temperature was investigated.

(Test Method) First, two kinds of commercially available sintered alumina abrasive grains manufactured by the sol-gel method were manufactured by USA 3M. There are two points based on the following US patents.

No. US Patent Specification Maker Product Name 1 4744802 USA 3M Cubitron 2 4881951 USA 3M Cubitron-321

Next, the above Cubitron and Cubitron-321 abrasive grains were put into an alumina crucible at 1000 ° C.
To 1300 ° C. for 6 hours, and the changes in the density, hardness and crystal of the abrasive grains after that were investigated. The results are shown in Table 1. The crystal size was measured from the results of SEM observation of the fracture surface of the abrasive grains shown in FIGS.

[0033]

[Table 1]

From the results shown in Table 1, it can be seen that the sintered alumina abrasive grains produced by the sol-gel method undergo crystal growth at 1200 ° C. and the abrasive grains are altered. Therefore, when producing a vitrified grindstone using the sintered alumina abrasive grains produced by such a sol-gel method,
The firing temperature needs to be 1200 ° C. or lower.

[0035]

[Experimental Example 2] Next, the crystalline aluminous abrasive grain produced by the sol-gel method has a smaller crystal grain size and is more active than the conventional fused aluminous abrasive grain, and is easily affected by the vitrified binder to form a vitrified binder. Since it is considered that a reaction may occur, the presence or absence of alteration of the sintered alumina abrasive grains with respect to the vitrified binder was investigated.

(Test Method) A test piece for investigating the degree of reaction was manufactured as follows.

(I) Sintered alumina-based abrasive grain No. 24 manufactured by 3M Company, USA ... 2 g (trade name: Cubitron-321) (ii) Noritake Company Limited's vitrified binder No. 201 to No. 203 …… 5g (iii) Tap water …… 5g

The used vitrified binders No. 201 to No. 203 manufactured by Noritake Co., Ltd. are made from a normal vitrified binder composed of feldspar, clay and frit glass, and its chemical composition. Is shown in Table 2.

[0039]

[Table 2]

The ingredients listed in (i), (ii) and (iii) above were placed in a mortar in the amounts indicated in order, mixed thoroughly and the diameter was 10
mm pellets with a height of 10 mm are formed, and the firing temperature is 100
The maximum temperature of 0 ° C was maintained for 6 hours, and the mixture was allowed to cool to room temperature and allowed to cool.

Next, in order to check whether the surface layer of the abrasive grains has been damaged and the surface layer of the abrasive grains has been altered, the pellets containing the sintered alumina abrasive grains after firing are polished, and a microhardness meter (manufactured by Akashi Seisakusho) ( Micro Vickers), as shown in FIG.
The hardness of the boundary portion between the vitrified binder and the sintered alumina abrasive grains was measured at intervals of 25 μm from the position 5 μm from the surface of the abrasive grain toward the center of the abrasive grain, and the degree of deterioration of the surface layer of the abrasive grain was measured.

The measurement conditions are as follows. (Measurement model: MVK-G1000 type (manufactured by Akashi Seisakusho) 300 g load, 10 seconds, diamond Vickers indenter

Table 3 shows the results of the depth from the abrasive grain surface layer to the central portion and the Vickers hardness, and FIG. 4 is a graph of the depth from the abrasive grain surface layer to the central portion (μm) vs. Vickers hardness (GPa). Indicated.

[0044]

[Table 3]

From Table 3 and FIG. 4, vitrified binder
No. 203 (Na ₂ O 6.0 wt%, Na ₂ O, K ₂ O, C
In the case of using the total amount of aO and MgO 4 species (hereinafter referred to as the total amount of modified oxides) of 10 wt%) and the unfired (raw) type, hardness was hardly reduced at the position of 5 μm from the surface layer of the abrasive grains. However, binder No. 201 (Na ₂ O 13.5w
t%, the total amount of modified oxides was 16 wt%), the hardness was significantly reduced at the position of 5 μm from the surface layer as compared with the central portion. Also, binder No. 202 (Na ₂ O 9.
In the case of using 0 wt% and the total amount of modified oxides of 12.5 wt%), it was slightly deteriorated at a position of 5 μm from the surface layer.

Therefore, binder No. 201 (Na ₂ O 13.5
wt%, total amount of modified oxides 16 wt%) 1000
It was found that in the case of firing at 0 ° C., up to the position of 5 μm in the surface layer, it was deteriorated by the vitrified binder.

[0047]

Example 1 Next, in order to examine how the degree of reactivity between the vitrified binder and the sintered alumina abrasive grains affects the grinding performance, a grinding stone for a grinding test was manufactured and a grinding test was conducted. .

(Test method) Vitrified binder (No.
201, 202, 203), sintered alumina-based abrasive grains Cubitron-321 and dextrin in the proportions listed in Table 4, respectively, and molded, followed by firing at 1000 ° C. for 6 hours,
Grinding wheels A, B and C were manufactured.

The outer diameter of these grindstones is 180 m.
m, the thickness is 19 mm, and the inner diameter is 76.2 mm. The difference in the amount of the vitrified binder between the grindstones A to C is to make the working hardness during grinding of the grindstones almost equal.

[0050]

[Table 4]

Next, the abrasive grain ratio of the grindstone after firing, the binder ratio,
The grindstone specific gravity, the Ogoshi bond degree, and the bending strength were measured. The results are shown in Table 5.

[0052]

[Table 5]

Further, a grinding test was performed on these grindstones A, B and C. For comparison, a grindstone D made of fused alumina type single crystal abrasive grains (manufactured by Taiheiyo Random Co., Ltd .; No. 32A, No. 60) having the same working hardness as the grindstones A, B and C was manufactured.

The grinding stone D of the comparative example has a firing temperature of 1200.degree.
Grindstone specific gravity 1.95, abrasive grain rate 46.1% by volume, binder rate 7.2% by volume, degree of Ogoshi bond 0.63 mm, bending strength 306 kg / cm ²
It is a normal whetstone.

(Grinding test conditions) Machine: Heioka Okamoto CFG-52AN Grinding wheel peripheral speed: 2000 m / min Depth of cut: ΔR 20 μm / pass wet plunge Do
wn Cut Work Material: SUJ-2 (HRC60) Dimensions: Length 100 x Height 50 x Width 10 (mm) Work Width: 10 mm Grinding Oil: Water-soluble Grinding Oil Noritake Co. Ltd. Noritake Cool K
82B 80 times liquid dresser: single stone

The results of this grinding test are shown in Table 6.

[0057]

[Table 6]

As is clear from Table 6, the grindstones of Examples B and C had a grinding ratio of 2.2 to 2.8 times that of the grindstone of Comparative Example D, had a good surface roughness, and had a low power consumption and a low noise. Showed good grinding performance.

However, Example A (vitrified binder
The grindstone of No. 201) had the same grinding ratio, the same surface roughness and the same noise as the grindstone of Comparative Example D, but the power consumption was high.

Therefore, it was found that the difference in performance between the grindstone A and the grindstones B and C was due to the fact that the surface layer of the sintered alumina abrasive grains of the grindstone A was further deteriorated by the vitrified binder.

Then, next, the grindstone A (calcined at 1000 ° C.)
The thickness of the reaction layer of the grinding stone C (calcined at 1000 ° C.) with the vitrified binder on the surface layer of the sintered alumina-based abrasive grains is determined by Shimadzu Corporation's electronic micro-partial analyzer (EPMA) (model: wavelength dispersion type). , ASM-SX).

As the test piece, pieces of the grindstones A to C were embedded in an epoxy resin and lapped so that the grindstone surface became a mirror surface after the epoxy resin was cured.

E. P. M. The results of observing the reaction layer of the abrasive grains of the grindstone A and the vitrified binder with A are shown in FIGS. 5 and 6. (A) in FIG. 5 is a SEM photograph of the boundary surface between the abrasive grains and the vitrified binder, and FIGS. 5 (b) and (c) show Na and K elements at the same place as the SEM observation place in (a). E. P. M. It is the result of the area analysis of A. Also, FIG.
(A), (b), and (c) are E.V. of each element of Al, Mg, and Ca at the same place as the SEM observation place of FIG. P.
M. It is the result of the area analysis of A.

Here, as shown in FIG. P.
M. When the result of the surface analysis of A was carefully observed, it was observed that Na element slightly penetrated into the sintered alumina abrasive grains.

Therefore, line analysis of the Na element is carried out at the same Na surface-analyzed portion of the same grindstone A, and the Na element in the vitrified bond is transferred to the sintered alumina abrasive grains due to the difference in the Na element concentration. It was measured whether it had penetrated to some extent.

FIG. 7 shows the result of actual line analysis of Na element. The penetration depth of the Na element is the distance ^* A between the portion where the concentration of Na element is high and the portion where the concentration of Na element is low as shown in FIG.

Table 7 shows the penetration depth of the Na element in the grindstones A to C.

[0068]

[Table 7]

From the results shown in Table 7, assuming that the penetration depth of Na element is the thickness of the reaction layer with the vitrified binder, the grindstone A
Is about 2.5 times as thick as the grindstone C. Therefore, it is considered that the sintered alumina-based abrasive grains of the grindstone A were considerably deteriorated by the vitrified binder, and thus the original performance of the abrasive grains could not be exhibited.

[0070]

[Example 2] Using the vitrified binder No. 112 manufactured by Noritake Co., Ltd., the materials listed in Table 8 were mixed at a predetermined ratio and molded, followed by firing at 1000 ° C to manufacture the grindstones E and F. .

The chemical components of the vitrified binder No. 112 were 65% silica, 11% alumina, 13% boron oxide, 7% sodium oxide, 2.5% potassium oxide, 1%.
% Magnesium oxide and 2.5% calcium oxide (the total amount of modified oxides is 13.0 wt%).

[0072]

[Table 8]

Next, the abrasive grain ratio of the grindstone after firing, the binder ratio,
Table 9 shows the results of measuring the specific gravity of the grindstone, the degree of Ogoshi bond, and the bending strength.
Shown in.

[0074]

[Table 9]

On the other hand, pellets of abrasive grains and a vitrified binder were produced in the same manner as in Example 1, and after firing at 1000 ° C., the pellets were polished, and the hardness at a position of 5 μm from the surface layer of the abrasive grains was measured to be 19.9 GPa. there were.

Further, a grinding test was conducted on the grindstones E and F. The grinding test conditions are the same as in Example 1. In Comparative Example D, the same 32A grindstone as in Example 1 was used. The results are shown in Table 10.

[0077]

[Table 10]

As is apparent from Table 10, the grindstones of Examples E and F showed a significant improvement in grinding performance as compared with the grindstone of Comparative Example D.

Next, from the surface of the abrasive grains of the grindstone of the grindstone E, the E.V. of Na, K, Mg, and Ca elements in the vitrified binder were added.
P. M. Perform A-line analysis (see FIGS. 9 and 10), Na,
The penetration depth of each element of K, Mg and Ca was measured in the same manner as in Example 1.

The results are shown in Table 11.

[0081]

[Table 11]

From the results shown in Table 11, the penetration depth of each element is 10
It is less than μ, and from this result, the reaction layer of the E stone is 10 μ
Was found to be less than.

[0083]

As described above, according to the vitrified grindstones according to claims 1 to 4, the sintered alumina-based abrasive grains produced by the sol-gel method do not deteriorate in performance, and the excellent performance of the sintered abrasive grains is maintained. It is possible to provide a vitrified whetstone that exhibits the above. The performance of this vitrified grindstone is remarkably superior in the grinding ratio and the grinding amount as compared with the conventional fused alumina abrasive grains.

According to the method of manufacturing a vitrified grindstone according to the fifth to seventh aspects, the vitrified grindstone having the above characteristics can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a SEM photograph showing an abrasive grain fracture surface of sol-gel method sintered alumina (No. 1) used in Experimental Example 1,
(A) is a raw abrasive material, (b) is a material after firing at 1200 ° C. for 6 hours, and (c) is a material after firing at 1250 ° C. for 6 hours.

FIG. 2 is an SEM photograph showing a fractured surface of abrasive grains of sol-gel method sintered alumina (No. 2) used in Experimental Example 1,
(A) is a raw abrasive material, (b) is a material after firing at 1200 ° C. for 6 hours, and (c) is a material after firing at 1250 ° C. for 6 hours.

FIG. 3 is an SEM photograph showing a press-fitting position of a Vickers indenter at a boundary portion between a vitrified binder and abrasive grains.

FIG. 4 is a graph showing the relationship between the depth (μm) from the surface layer of the abrasive grains to the center and the Vickers hardness (GPa).

5 is a photograph showing SEM observation and EPM A surface analysis results of the reaction layer of the grindstone A in Example 1, FIG.
Is a SEM photograph of the interface between the abrasive grains and the vitrified bond,
(B) and (c) are E.V. of Na and K elements at the same location as the SEM observation location in (a). P. M. It is the result of the area analysis of A.

FIG. 6 is an E. image of the same place as the SEM observation place of FIG.
It is a photograph showing a PMA surface analysis result, (a), (b),
(C) is an E.V. of each element of Al, Mg, and Ca. P.
M. It is the result of the area analysis of A.

7 is a SEM photograph in which the Na elemental line analysis results of the reaction layer of the grindstone in Example 1 are also displayed, (a) shows the line analysis result of the grindstone C, and (b) shows the line analysis result of the grindstone A. FIG. Show.

FIG. 8 is a schematic diagram for explaining the penetration depth of Na element.

9 is an E.V. of the reaction layer of the grindstone E in Example 2. FIG. P.
M. It is the SEM photograph which also displayed the A line analysis result,
(A) and (b) are results of Na and K elements, respectively.

10 is an E.V. of the reaction layer of the grindstone E in Example 2. FIG. P.
M. It is the SEM photograph which also displayed the A line analysis result,
(A) and (b) are results of Mg and Ca elements, respectively.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 19, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

FIG. 1 is a SEM photograph showing a grain structure of a fractured surface of an abrasive grain of sol-gel method sintered alumina (No. 1) used in Experimental Example 1, where (a) is a raw abrasive and (b) is 1200 ° C. After firing for 6 hours, (c) is after firing at 1250 ° C. for 6 hours.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

2 is a SEM photograph showing a grain structure of an abrasive grain fracture surface of sol-gel method sintered alumina (No. 2) used in Experimental Example 1, where (a) is a raw abrasive and (b) is 1200 ° C. After firing for 6 hours, (c) is after firing at 1250 ° C. for 6 hours.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

FIG. 3 is a set of ceramic materials showing a press-fitting position of a Vickers indenter at a boundary between a vitrified binder and abrasive grains.
It is an SEM photograph of a woven fabric.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

FIG. 5: Ceramic of reaction layer of grinding wheel A in Example 1
SEM observation photograph showing the structure of the material and E. P. M. It is an X-ray photograph showing the results of praying on the A side, (a) is an SEM photograph showing the structure of the ceramic material at the boundary surface between the abrasive grains and the vitrified bond, and (b) and (c) are respectively (a). SE
E.M. of each element of Na and K at the same place as the observation site. P. M.
It is an X-ray photograph which shows the result of the surface analysis of A.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

FIG. 6 shows an E.I. image at the same place as the SEM observation place in FIG.
P. M. It is an X-ray photograph showing the A-side analysis result, (a),
(B) and (c) are E.V. of each element of Al, Mg, and Ca, respectively. P. M. It is an X-ray photograph which shows the result of the surface analysis of A.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

FIG. 7 is a set of ceramic materials in which X-ray photographs of the Na elemental ray analysis results of the reaction layer of the grindstone in Example 1 are also displayed.
It is a SEM photograph showing a weave , (a) is an SEM showing the structure of the ceramic material and the X-ray photograph showing the line segment result of the grindstone C.
Superimposition of photographs , (b) X showing the line segment folding result of the grindstone A
Overlay of line image and SEM image showing structure of ceramic material
Indicates the match .

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] Figure 9

[Correction method] Change

[Correction content]

9 is an E.V. of the reaction layer of the grindstone E in Example 2. FIG. P.
M. Ceramic showing the X-ray photograph of the result of A-line segmentation
4A and 4B are SEM photographs showing the structure of the black material , and
X-ray photographs and Serra indicating Na, the results of K respective elements respectively
It is an overlay of SEM photographs showing the structure of the Mick material .

[Procedure Amendment 8]

[Document name to be amended] Statement

[Name of item to be corrected] Fig. 10

[Correction method] Change

[Correction content]

10 is an E.V. of the reaction layer of the grindstone E in Example 2. FIG. P.
M. A ceramic display that also displays an X-ray photograph of the A-ray analysis results.
4A and 4B are SEM photographs showing the structure of the black material , and
Is an X-ray photograph showing the results of each element of Mg and Ca and
It is a superposition of SEM photographs showing the structure of a lamic material .

Claims (7)

[Claims] 1. A vitrified grindstone obtained by firing abrasive grains containing at least 5% by weight or more of sintered alumina abrasive grains produced by a sol-gel method and a vitrified bond at a predetermined temperature, which is formed during firing. The vitrified grindstone, wherein the thickness of the reaction layer at the interface between the abrasive grains and the vitrified binder is less than 10 μm (excluding 0 μm) from the surface layer of the abrasive grains to the inside thereof. 2. The vitrified grindstone according to claim 1, wherein the sintered alumina abrasive grains are abrasive grains made of aluminum oxide containing a rare earth metal. 3. Alumina crystal grain size after calcination is from 0.05 to
It is 0.8 micrometer, The vitrified grindstone of Claim 1 or 2 characterized by the above-mentioned. 4. The vitrified grindstone according to claim 1, wherein the total amount of the modified oxide contained in the vitrified binder is 20 wt% or less. 5. An abrasive containing at least 5% by weight or more of sintered alumina-based abrasive produced by a sol-gel method and a vitrified binder are fired at a firing temperature of 1200 ° C. or less,
Method for producing a vitrified grindstone for manufacturing a vitrified grindstone in which the thickness of the reaction layer at the interface between the abrasive grain and the vitrified bond formed during firing is less than 10 μm (excluding 0 μm) from the surface layer of the abrasive grain to the inside thereof . 6. The sintered alumina abrasive grains are abrasive grains made of aluminum oxide containing a rare earth metal, and
The method for producing a vitrified grindstone according to claim 5, wherein the sol containing an alumina seed and / or a rare earth metal is produced by drying and then heat-treating the sol. 7. The method for producing a vitrified grindstone according to claim 5, wherein the total amount of the modified oxide contained in the vitrified binder is 20 wt% or less.