DE1596726C - Semi-crystalline glass objects of high strength and minimal deformation and processes for their production, in particular for varying the thermal expansion behavior - Google Patents

Description

Semicrystalline glass objects with immense mechanical strength and a ceramic-like appearance are already known (US Pat. No. 17,881). These objects are made out of glasses and released through a heat treatment, whereby the crystalline phase is primarily rdierite, mullite, sapphire or tridymite. _{At least 6 percent by weight of zirconium dioxide ZrO 2} d, optionally about 1.5 percent by weight of other imparing agents, serve as the im-forming agent or crystallizer. Glass objects with a ceramic-like appearance and a low degree of healing in a crystalline quartz phase are also known (SA patent specification 2 971 853). This is η lithium aluminum silicate base glasses, the transformation takes place with the help of light-sensitive objects. Up to now, however, it has not been possible to produce semi-crystalline glass objects which have a large proportion of crystalline quartz phase, although the nucleation did not take place on the photomechanical basis. This applies in particular to basic glasses based on magnesium, aluminum and silicon dioxide.

The invention now brings semi-crystalline glass objects made of a base glass containing magneum oxide, aluminum oxide and silicon dioxide, where the main part of the crystalline phase is quartz. The ärmedenjnungskoeffizient and thus the behavior ir glass objects to temperature change ßt The inventive glassware ι adjust a wide range, so that it · succeed without Schwiegkeiten, which insbesondre are glass objects as hearth and tableware manufacture. These objects are characterized by a low content of internal stresses and also of stresses in the glaze. By setting a desired coefficient of thermal expansion for the glass compositions according to the invention, conventional glazes, which are desirable for decorative reasons for cooker and tableware, can be used. This was not possible with the known glasses, a the coefficient of thermal expansion could not be adjusted for the usual glazes. So when the semi-crystalline glass objects are fired and cooled, cracks and deformations occur. So far, efforts have been made to achieve complete or almost complete crystallization from glassy masses for the production of objects with a ceramic-like appearance. The invention takes a different route. In the glass objects according to the invention, the proportion of λ-quartz is less than about 40 percent by volume, as can be determined by X-ray diffraction analysis. «- Quartz is the main part of the crystalline phase, so it is always present in a larger proportion than the other components of the crystalline phase and usually even in a significantly larger proportion.

The invention thus relates to semicrystalline glass objects with a coefficient of thermal expansion between 34 and 125 χ K) " ⁷ /" C, containing 55 to percent by weight SiO ₂ , 9 to 23 percent by weight _{I 2} O ₃ , 8.5 to 13 percent by weight MgO, 1 to 7 percent by weight B ₂ O ,, 1 to 6 percent by weight TiO _{2 and} 2 to 5.75 percent by weight ZrO ₂ , the main proportion of the crystalline phase, preferably K) being 40 percent by weight, is quartz. The glass objects can contain 1 to 5 percent by weight ZnO and / or> bO or 0.5 to 2 percent by weight Li ₂ O, LiF and / or CrF ₂ as flux. For preferred glass items, the sum is

SiO, + AUO ₃ + MgO 5.

at least 85 percent by weight. Particularly good, high-quality and beautiful objects are those containing 58 to 61 percent by weight SiO ₂ , 15 to 20 percent by weight Al ₂ O ₃ , 8.5 to 11 percent by weight MgO, 1.75 to 3 percent by weight B ₂ O ₃ , 2.5 to 4 percent by weight TiO ₂ and 3.5 to 4 percent by weight ZrO ₂ . The glass objects according to the invention are produced in such a way that the oxidic components are melted together and objects are formed from the melt in the usual way. These items are then heated according to the invention with a heating rate to 150 ° C per hour to a temperature of 927-1038 ⁰ C and heated for 15 minutes to 2 hours at this temperature.

It showed 'that the glass articles thus obtained mm a modulus of rupture of between about 21.1 and 127 kg / ² in a coefficient of thermal expansion between about 34 and 125 χ 10 ^-7 / ° C hold. The modulus of rupture and the coefficient of thermal expansion vary somewhat with the heat treatment.

It was found that "quartz" is only obtained as the main component of the crystalline phase in the glasses according to the invention if a certain proportion of boron oxide, zirconium dioxide and titanium dioxide is present in the basic glasses, which contain magnesium oxide, aluminum oxide and silicon dioxide. The cause of this phenomenon has not yet been fully clarified, but it is believed that phase separation occurs due to a state of order in a narrow area. It is assumed that in the presence of B ₂ O _{3 there is} a metastable state in the glass and that -quartz crystallizes out only as a result of the joint presence of TiO ₂ and ZrO _2. In other words, the presence of TiO ₂ and ZrO ₂ door ■ the crystallization of the quartz in the crystalline phase is a prerequisite for the special properties of the semi-crystalline glass objects. During the heat treatment there is no crystallization of the quartz if ZrO ₂ or TiO ₂ are missing.

The metastable conditions are not only necessary for the crystallization of the quartz, but also prevent deformation of the glass objects during heat treatment in the frame of glazing or decorating. Finally, this metastable state also favors opacity of glass objects. ■ ·

For the production of the glass objects according to the invention the usual raw materials as well as the usual melting and molding processes are suitable on the existing systems. It was found that the physical properties of the Glass articles according to the invention depend to some extent on the tempering treatment for Crystallization, d. H. the heating rate and the tempering time and temperature. The heating rate should be up to 150 C / hour and up to about 7 (KV C, maximum 1038 "C. The The dwell time at the maximum temperature should last up to about 2 hours.

The invention is illustrated by the following examples.

Examples 1 to 5
In Table I is the offset. i.e. the weight proportions of the raw products for the manufacture of the glasses.

Table I.

Uppercase /

Flint

Boric acid

Magnesite,. '

Hydrated clay
Burnt clay ..

Titanium dioxide

Zircon

Red lead

example 1 Example 2 Example 3 Example 4 Example 5

2000 282.5 426.5

350.7 127.0 174.9

2000
115
378
999

134.
184.5
110.6

2070 115 307,

1105

134 184.5

1929

115

307 1211

134 184.5

A test rod was formed from the glass melt, cooled to room temperature and then with heated to 982 "C at a rate of 55 ° C / hour and held at this temperature for 0.5 hours, then cooled to room temperature. The bars were white and translucent. the X-ray diffraction analysis (Klug, Alexander, »X-Ray Diffraction Procedures «) showed the presence of« quartz. Also the thermal expansion regulations showed the presence of λ-quartz in the crystalline as a result of the characteristic quartz transformation Phase.

The strength was determined on test bars with a diameter of 3 mm, namely after usual procedures at two support points and one load point.

Tables show the analysis of the glass objects of Examples 1 to 3 together with the melting temperature, the strength determined in the tests and the coefficient of thermal expansion between 38 and 316 ° C. The tempering conditions in Examples 1 to 4 were the same, in Example 5 the rod was heated to 927 "C and left ^{at this temperature 1 for 2 hours.}

The deformation of the rods during this heat treatment was also determined, namely the Angle from the horizontal found, which is in a piece of 19 mm of the rod, which is not was supported, resulted. A deformation could not be observed in the glass rods in question will.

Table II example 1 Example 2

Weight percent Example 3,

Example 4 Example 5

SiO ₂

B ₂ O ₃

Fe ₂ O ₃

TiO ₂

Al ₂ O ₃

CaO

MgO

ZrO ₂

Na ₂ O

PbO

Fp . ^: C

Strength, kg / mm ²

63.53

4.86

. 0.07

3.88

10.85 0.16

12.97 3.63 0.04

1482 32.7

63.45 1.88 0.08 3.89

13.86 0.16

13.00 3.64 0.06

1482 24.5 58.78

1.83

0.04

. 3.78

18.36

: 0.13

-, 10.53
3.54

3.0
1427
28.6

61.41
.1.85
0.04
3.83

"20.50
0.11
8.69
3.58.

l "482 '
- ■ .87.9

. -58.59 /

.- "1.89

0.04

3.91

22.94

0.11

3.66

1482. 56.2

Expansion coefficient 73.3 χ 10 " ⁷ / C.

Tables III and IV were then compiled using the glass from Example 1 of the In 65 tables. The lingering the heating rate and the residence time in the tests for Table III at the crystallization temperature to the mechanical 1 hour, the heating speed in Table IV see properties examined. The values are in 55 C. hour.

1 596 726 5 Table III Out

Elevation speed C hour to 982 C

149

110

55

. 18th

Thermal expansion

coefficient χ 10 " ⁷ - 'C

(38 to 316 C)

. - 4U6

58.0

90.5

, 111.2

Table IV

Strength kg'mrrr

22.9 24.5 29.0 37.9

Maximum
Crystallization
temperature
C. Dwell Cit
hours Thermal expansion
kocffizicnt
χ ICT ⁷ / C
(38 to 316 "C) strength
kg mm ² 966 ■■■ . 0 43.8 21.4 982 0 51.8 19.7 982 0.25 67.3 37.8 982 0.25 73.3 32.7 982 1 ' 90.5 30.0

Table III thus shows that the coefficient of thermal expansion increases with increasing heating rate and strength increase. Likewise takes. the coefficient of thermal expansion with increasing residence time towards crystallization temperature.

Eg 6 to 10

In these examples, the dependence of the crystal formation of quartz on the proportions of TiO ₂ . ZrO ₂ and B ₂ O ₃ can be determined. In these glasses, the proportions of magnesium oxide, aluminum oxide and silicon dioxide correspond to the corresponding values of the glasses according to the invention, which however only contain titanium dioxide (Examples 6 and 7), titanium dioxide and boric acid (Examples 8 and 9) and titanium dioxide and zirconium dioxide (Example 10). The X-ray diffraction diagram showed that the test bars from Examples 8 to 10 did not contain any γ-quartz in the crystalline phase. The strength and coefficient of thermal expansion, as well as deformation, opacity and color of these products were very uneven.

Table V Example 6 Example 7

Weight percent Example 8

Example 9 Example 10

Fe ₂ O ₃

TiO ₂

Al ₂ O ₃ .:

CaO

MgO

ZrO ₂

Na ₂ O

Crystallization temperature,
⁰ C

62.25

0.04 6.11 22.12 0.11 9.38

927

59.82

0.04 9.77 21.25 0.11 9.01

927 61.32
3.21
0.07

11.55

10.77
0.16

12.88

0.04
982

63.81
3.35
0.07
8.02

11.15
0.16

13.40

0.04
982

66.78

0.07
4.08

11.40
0.17

13.63
3.82
0.05

982

Examples 11-14

The following table shows that not only ZrO ₂ , B ₂ O ₃ and TiO ₂ must be present for a crystalline phase mainly of "quartz, but that these oxides must also be present in a very specific proportion. It follows from this that with otherwise equal proportions of TiO ₂ and ZrO _2, only the proportions of B ₂ O ₃ varied between 1.67 and 7.69%. The previous examples 1 to 10 should be added to Table VI. The crystallization conditions were the same everywhere, namely "0.5 hours at 982 ° C.

45 CaO .... Example 11 Weight percent Example 13 Example 14 ₀ MgO .... 0.16 Example 12 0.16 0.15. ZrO ₂ 13.41 0.16 12.78 '12:59 Na ₂ O ... 3.75 13.19 3.58 3.52 0.04 3.69 0.04 ' 0.04 0.04

Table VI Example 11 Example 12 Example 13 Example 14 65.66 64.58 62.57 61.64 Weight percent ■ 1.67 3.30 6.30 7.69 SiO ₂ ...: 0.07 0.07 0.07 0.07 B ₂ O ₃ .... 4.01 3.94 3.82 3.76 Fc ₂ O ₃ ... ■ 11.21 11.03 10.69 10.53 TiO ₂ .... AI ₂ O., ...

The articles according to Examples 1, 11 and 12 contained quartz as the main part of the crystalline phase. Although the proportion of B ₂ O ₃ can be increased slightly over 6 percent by weight, if the proportions of ZrO ₂ and TiO _{2 are also} increased, it was found that more than 7 percent by weight largely hinder the formation of quartz crystals.

Example 5 to 7

These examples are intended to show the influence of different amounts of ZrO ₂ . The composition of Example 1 also belongs to these investigations. Annealing conditions: 982 C. 0.5 hours. From these investigations it follows.

that the strength of example 1 with 32.2 kg / mm ² in example 16 has already decreased to 18.7 kg / mm 2. The test rod from Example 17 was unsuitable for these investigations. If the TiO ₂ content is increased together with the proportion of ZrO ₂ , no decrease in strength is found. _{If the proportion of ZrO 2} is more than about 5.75 percent by weight, precipitation often occurs when the glasses melt. - "'.

Table VII ewicblsprozcr
Example 16 _ - ' 62.64
4.72 - U
Example 17 SiO, 62.21
4.65 B, 0, G
Example IS .63.08
4.79

Fe ₂ O ₃

TiO ₂

Al ₂ O ₃

CaO

MgO

-ZrO ₂

Na ₂ O

Weight percent example

0.07 3.82

10.69 0.16

12.78 4.57 0.04

example

0.07

3.77 10.53

0.15 12.59 - "-

5.48-

0.04

example

0.07

3.71 10.38

0.15 12.41 -

6.38 • 0.04

Examples 18 to

Using these examples, the influence of the proportion of TiO ₂ and together with ZrO _{2 will be} shown. Tempering conditions: 982 ° C, 0.5 hours.

Table VIII Example 18 example

Weight percent Example 20 Example 21

example example

SiO ₂ .
B ₂ O _3. ·
Fe ₂ O ₃
Τίφ.
Al ₂ O ₃
CaO.
MgO.
Na ₂ O
ZrO ₂ .

63.94 3.26 0.07 4.89

10.92 0.16

13.06 0.04 3.66

63.32 3.23 0.07 5.81

10.81 0.16

12.93 0.04 3.62 62.30
3.18
0.07
7.34

10.64
0.16

12.72
0.04
3.56

59.99 3.06 0.07

10.76

10.25 0.15

12.25 0.04

■ 3.43

63.48 3.22 0.07 4.82

10.76 0.16

12.86 0.04 4.59

62.44 3.14 0.07 5.65

10.50 0.15

12.55 0.04

.5.46.

In the glass rods of Examples 20 and 21, α-quartz was present in the crystal phase, but not in the other examples. The TiO ₂ content can be a little over. 6 percent by weight if the ZrO ₂ content is also higher, but higher proportions of TiO ₂ above 6 percent by weight no longer result in any further advantages.

Examples 24 to

The test bars of Examples 24, 25, 27 were held at 927 ° C. for 2 hours. The majority of the crystalline phase was α-quartz. The test bars of Examples 26, 28, 29 were heated to 982 ° C. for 0.5 hours held. Here, too, one places a crystalline. Phase with a lot of α-quartz solid.

Table IX Example 24

* · Example

Weight percent Example 26

■ Example 27

example example

SiO ₂ ..
AI ₂ O ₃ .
MgO ..
B ₂ O ₃ ..
ZrO ₂ ...
TiO ₂ ..
CaO ..
Fe ₂ O ₃ .
kg / mm ²

61.85

21.33

9.04

1.92

3.73

1.98

0.11

0.04

24.4

60.61

20.90

8.86

1.88

3.65

3.95

0.11

0.04

104 59.79

21.36

9.06

1.93

3.73

3.99

0.11

0.04

130.4

59.45 22.46 8.69 1.85 3.58 3.83 0.11 0.03

62.49

14.88

13.01

1.88

-3.64

3.89

0.16

0.05

44.2

62.53 ■ 16.91

10.97. 1.88

-3.65, 3.90 0.13 0.04

30.5

Examples 30 to 41

A certain proportion of lead oxide and / or zinc oxide up to about 5 percent by weight can advantageously be added to the Be meltdown. Calcium fluoride is also suitable as a flux. Lithium fluoride and lithium oxide. The lithium components are preferably introduced as spodumene or pentalite.

109644 16V

Table X

Example 30 Weight •.percent - oxide 60.00 Example 31 Example 32 Example! 33 SiO ₂ .... 18.74 56.68 59.40 58.23 Al ₂ O ₃ ... 10.75 19.55 20.49 20.08 MgO .... 1.86 8.29 8.69 8.51 B ₂ O ₃ .... 3.61 5.29 · 1.85 1.81 ZrO ₂ .... 3.86 3.41 • 3.58 3.51 TiO ₂ .... 0.13 3.65 3.82 3.75 CaO .... 0.04 0.10 0.11 0.10 Fe ₂ O ₃ ... 1.00 0.03 0.03 0.03 PbO .... - 3.00 - - ZnO .... -. • 2.04 3.97

(Continuation)

10 oxide Example 3S Weight
Example 39 percent
Example 40 Example 41 ₅ Na ₂ O ...
ZrO ₂ ....
LiF 0.04
3.64
1.01 0.04
.3.64
2.01 ' 0.04
3.63
2.00 0.04
3.63 CaF ₂ 4.00

Example 34 Weight percent Example 36 Example 37. oxide 63.80 Example 35 64.56 64.69 SiO ₂ .... 4.06 64.07 3.29 3.30 B ₂ O ₃ .... 0.07 4.08 0.14 0.04 Fe ₂ (X ...
TiO ₂ I ... 3.90 0.11 3.94 3.95 Al ₂ O ₃ ... 10.88 ■ 3.91, 11.02 11.03 CaO .... 0.11 10.93 / 0.12 0.10 MgO: .. '. 13.02 0.11. .11.66 12.70 Na ₂ O ... * 0.05 ■ 12.09 0.06 0.04 ZrO ₂ .... 3.58 0.06 3.63 3.63 K ₂ O .... • 0.02 3.60 0.06 - · Li ₂ O .... 0.50. ■ 0.04 1.51 - LiF 1.00 - 0.50 " -

Annealing conditions: for Examples 30 and 34 to 41 for 0.5 hours 982 ° C, examples 31, 32, 33 927 ⁰ C. The strengths were 28.7 to 108 kg / mm ^2.

In the case of the B ₂ O ₃ -containing glass batches, it must be taken into account that boric acid is somewhat volatile under the prevailing conditions. The proportions of boron oxide in Examples 1 and 12 are thus about 1 percent by weight below the calculated values. The values given in the tables are the analytical values.

Four glasses were melted, the composition of which is shown in the first table below, pie glasses 1 and 2 represent a boron-free variation of the glasses according to the invention, samples 3 and 4 correspond to examples 19 and 22 from US Pat. No. 3,117,881 individual glasses were melted at .1480 ⁰ C., refined Hour 16, then poured into test and subjected it to various heat treatments and examinations.

Table 1

"■ (continued) Weight percent Example 40 Example 41 oxide Example 39 64.61 64.70 ■ Example 38 64.70 3.30 3.30 .SiO ₂ .... 64.69 3.30 0.04 0.03 B ₂ O ₃ .... 3.30 0.04 3.95 3.95 Fe ₂ O ₃ ... 0.04 3.95 11.17 11.06 TiO ₂ ...; 3.95 11.03 0.09 0.07 Al ₂ O ₃ ... 11.03 0.09 11.18 9.19 CaO .... 0.10 11.20 MgO .... 12.20

1 Weight percent 2 3 4th '58 sample 58.25 46.6 45.1 23 23 30.3. 29.3 .SiO ₂ .... 11.02 11.02 11.2 11.2 Al ₂ O ₃ ... 6th 5.75 . 8th 8th MgO .... 1.98 1.98 1.5 1.5 ZrO ₂ .... Ο ^: 0 0.5 3 TiO ₂ .... Ι 00% 100% 97.10% 99.51% B ₂ O ₃ ....

Three heat treatments were carried out with the test rods from glass samples 1 to 4, namely according to Tables 3 and 4 according to the invention or according to Examples 9 to 22 of U.S. Patent. After these heat treatments, the coefficient of thermal expansion, strength and the turning angle is determined as a characteristic of the deformation. ".

table

I. Heating up to 980 "C, dwell time
lesson
a) l66 "C / Slundcx 10 ⁷

(38 to 315 "C)

■ kg / mm ²

Turn £

sample

32.2

35 "33.2
15.5
39.5

51
70

.1

29 90

continuation

sample

b) 55 ° C / hour x 10 " ⁷

(38 to 315'C) .....

kg / mm ^2. "

Turn £

2. Heat up to 965 C with
55 ° C / hour χ ΙΟ " ⁷ ..-.-.

kg / mm ²

Turn £

3. According to U.S. Patent 3,117,881, Examples 19 and 22 each for 1.5 hours 785, 925 and 1065'C

kg / mm ² :

Turn £

40.8 24.6 7.5 "

30.9 15

. 7.5

8.8 '

24 '

minor chipping 42
22.7

31.6
16
6'-

11.25

45 'chipping

43.5.
38 '

42
47.5 '

51 82.5

21.6 ■ 80 "

. 38.5 85-

30.6 90 °

The test rods subjected to the various heat treatments were then x-rayed investigated to establish the crystalline phase system.

Table 3

Heat treatment after Ib 3 sample disturbed ß-quartz disturbed / i-quartz 1 + Zirconate titanate + Zirconate titanate disturbed /? - quartz disturbed // - quartz 2 + Zirconate titanate + Zirconate titanate disturbed / f-quartz disturbed / i-quartz 3 + Zirconate titanate + Zirconate + Sapphire + Sapphire Sapphire Zirconate 4th + disturbed + Sapphire / f-quartz + Zirconate titanate

30th

35

40

45

The essential feature of the semicrystalline glasses according to the invention is the appearance of α-quartz in the crystalline phase. This causes a particularly favorable combination of properties the glass objects can be reached, namely

a) low deformation,

b) with the help of a glass composition it is possible to produce glasses with a wide range of Coefficient of thermal expansion can only be achieved by heat treatment, and

c) high strength. .

From the above test results it can be seen that samples 3 and 4 have high strength have, but their deformation is so significant that this is a serious disadvantage in many fields of application represents. If one compares the values for the turning angles of the comparison tests with the Examples 1 to 5 according to the invention (Table 2) and takes into account that under the same test conditions no deformation (bending angle 0) occurs, the superiority of the invention Products obviously.

55 As noted, the conditions in the recrystallization can be after the invention of thermal expansion coefficient required of the finished glass objects in a simple manner by selecting influence. The coefficient of thermal expansion of the glass according to the invention according to Example 1 is between 41.6 and III, 2x10 ~ ^7, depending on the heat treatment. This is a very important factor in practice.

In summary, it can be said that in the case of the glasses assembled according to the invention with their main proportion of α-quartz in the crystal phase, high-quality products can be obtained can, which by the possible heat treatments in terms of their expansion behavior in the desired Way can be influenced. They have very good strength with minimal deformation.

Claims (7)

Patent claims: 1. Semi-crystalline glass objects of high strength and minimal deformation with a coefficient of thermal expansion between 34 and 125 χ 10 ~ ⁷ / "C (38 to 316 ° C), dadurchgeke η η ζ eich η et that they 55 to 66 percent by weight SiO ₂ , 9 to 23 percent by weight AIzQ ₃ , 8.5 to 13 percent by weight MgO and 1 to 7 percent by weight B ₂ O ₃ and as nucleating agents 1 to 6 percent by weight TiO ₂ and 2 to 5.75 percent by weight ZrO ₂ , the main part of the crystalline phase, preferably 10 up to 40 percent by weight, «quartz is. '".'_ ■ 2. Articles according to claim 1, characterized by a content of 1 to 5 percent by weight ZnO and / or PbO as flux. 3. Articles according to claim 1, characterized by a content of 0.5 to 2 percent by weight Li ₂ O, LiF and / or CaF ₂ as flux. 4. Articles according to claim 1, characterized by a sum of SiO ₂ + Al ₂ O ₃ + MgO ^ 85 percent by weight. 5. Articles according to claim 4, characterized by a content of 1 to 4.5 percent by weight of ZnO, PbO, Li ₂ O, LiF and / or CaF ₂ as flux. 13 14 6. Objects according to claim 1, characterized in that 7. Process for the production of the glass objects indicates that they stand 58 to 61 percent by weight according to claims 1 to 6, characterized SiO ₂ , 15 to 20 percent by weight Al ₂ O ₃ , 8.5 bis indicates that those formed from the melt 11 percent by weight MgO and 1.75 to 3 Ge objects for crystallization with a heating weight percent B ₂ O ₃ and as a nucleating agent 2.5 to 5 speed up to 150 ° C / hour to 927 to 4 percent by weight of TiO ₂ and 3.5 to 4 percent by weight heated to 1038 ° C and heated at this ex-.temperature for 15 minutes percent ZrO ₂ included. · Th to "be held for 2 hours." -