DE202021103861U1 - Disc-shaped, chemically toughened or chemically toughened glass articles - Google Patents

Abstract

Chemically toughened or chemically toughened, disk-shaped glass article (1) comprising a glass with a composition comprising Al2O3, SiO2, Li2O and B2O3, the glass and / or the glass article (1) at most 7 wt.% B2O3, preferably at most 5 wt. -% B2O3, particularly preferably at most 4.5% by weight B2O3.

Description

Field of invention

The invention relates to a disk-shaped, chemically toughened or at least chemically toughened glass article. Furthermore, the present disclosure also relates to a glass composition.

Background of the invention

Pane-shaped pre-stressed, in particular chemically pre-stressed and especially chemically highly pre-stressed glass articles are used in particular as so-called protective glasses (or covers or cover glasses) for mobile end devices such as smartphones or tablet computers. Compared to covers made of transparent plastics, these protective glasses are particularly more scratch-resistant, but they are also heavier.

Only chemically pre-stressed, disc-shaped glass articles are used as protective glasses for mobile devices. This is because these glass articles are even more resistant to mechanical wear and tear, so they have the wear resistance required for the application. In the context of the present disclosure, wear resistance is understood to mean the resistance of a product (or article, such as a glass article or a glass product) to mechanical loads, in particular to abrasive loads, scratches or impact loads. The term “wear resistance” or “strength” for short is therefore used generically in the context of the present disclosure for the mechanical resistance of a product or article. Special forms of wear resistance, or strength for short, are, for example, scratch resistance, flexural strength, impact resistance or preferably also hardness, whereby it has been shown that links between these loads are also possible and are of particular relevance in practical application. Such practical loads are, for example, the impact on a rough surface, especially when installed.

In addition to the requirements for good wear resistance, the disk-shaped glass article should also meet other requirements. In particular, the glass which the glass article comprises should be easy to manufacture, that is to say, for example, accessible to a melting process with a subsequent hot forming process, in which case devitrification should preferably not occur. The chemical resistance of the glass article is also of relevance, especially the acid resistance. This is to be seen in particular against the background that, although good resistance of the end product is necessary, on the other hand good pretensioning must also be given in an ion exchange process. It has been shown that good biasability in an ion exchange process generally correlates more with low chemical resistance, because the high mobility, particularly of alkali ions, which is advantageous for easy ion exchange, tends to be detrimental to chemical resistance.

Known chemically toughened glasses and / or chemically toughened or chemically toughened glass articles and / or methods for producing such articles are described, for example, in the patent family for US 2019/0016632 A1 with an already granted US patent US 9,593,42 B2 as a family member, the patent family for US 2018/0057401 A1 with an already granted US patent US 10,294,151 B2 as a family member, the patent family for US 2018/0029932 A1 with an already granted US patent US 10,259,746 B2 as a family member, the patent family for US 2017/0166478 A1 with an already granted US patent US 9,908,811 B2 as a family member who US 9,908,811 B2 , the patent family for US 2016/0122240 A1 with an already granted US patent US 10,239,784 B2 as a family member, the patent family for US 2016/0122239 A1 with an already granted US patent US 10,150,698 B2 as a family member, the patent family for US 2017/0295657 A1 with an already granted US patent US 10,271,442 B2 as a family member, the patent family for US 2010/0028607 A1 with an already granted US patent US 8,312,739 B2 as a family member, the patent family for US 2013/0224492 A1 with an already granted US patent US 9,359,251 B2 as a family member, the patent family for US 2016/0023944 A1 with an already granted US patent US 9,718,727 B2 as a family member, the patent family for US 2012/0052271 A1 with an already granted family member US 10,227,253 B2 , the patent family for US 2015/0030840 A1 with an already granted US patent US 10,227,253 B2 as a family member, the patent family for US 2014/0345325 A1 , the patent family for US 2016/0257605 A1 with an already issued US patent US 9,487,434 B2 as a family member, the patent family for US 2015/0239776 A1 with an already issued US patent US 9,517,968 B2 as a family member, the patent family for US 2015/0259244 A1 with an already issued US patent US 9,567,254 B2 as a family member, the patent family for US 2017/0036952 A1 with an already granted US patent US 9,676,663 B2 as a family member, the patent family for US 2018/0002223 A1 with an already granted US patent US 10,266,447 B2 as a family member, the patent family for US 2017/0129803 A1 with an already granted US patent US 9,517,968 B2 , the patent family for US 2016/0102014 A1 with an already granted US patent US 10,266,447 B2 as a family member, the patent family for US 2015/0368153 A1 with an already granted US patent US 9,676,663 B2 as a family member, the patent family for US 2015/0368148 A1 with an already granted US patent US 9,902,648 B2 as a family member, the patent family for US 2015/0239775 A1 with an already granted US patent US 10,118,858 B2 , the patent family for US 2016/0264452 A1 and the previously issued US patent US 9,902,648 B2 , the patent family for US 2016/102011 A1 and the previously issued US patent US 9,593,042 B2 , the patent family for WO 2012/126394 A1 , the patent family for US 2014/0308526 A1 and the previously issued US patent US 9,540,278 B2 , the patent family for US 2011/0294648 A1 and the previously issued US patent US 8,759,238 B2 , the patent family for US 2010/0035038 A1 and the previously issued US patent US 8,075,999 B2 , the patent family for U.S. 4,055,703 , the patent family for DE 10 2010 009 584 A1 , the granted German patent DE 10 2010 009 584 B4 and the US filing US 2016/0347655 A1 with the granted US patent US10351471 B2 , the patent family for CN 102690059 A and the already granted Chinese patent CN 102690059 B , the patent family for US2016 / 0356760 A1 and the previously issued US patent US 10,180,416 B2 , the patent family for WO 2017/049028 A1 with the already granted US property right US 9,897,574 B2 as a family member, the patent family for WO 2017/087742 A1 , the patent family for US 2017/0291849 A1 and the previously issued US patent US 10,017,417 B2 , the patent family for US 2017/0022093 A1 and the previously issued US patent US 9,701,569 B2 , the patent family for US 2017/300088 (A1) and the granted US patent US 9,977,470 B2 , the patent family for EP 1 593 658 A1 , the granted European patent EP 1 593 658 B1 as well as the US application US 2005/0250639 A1 and the patent family for US 2018/0022638 A1 and the previously issued US patent US 10,183,887 B2 . Chemically toughenable glasses can be differentiated into so-called aluminum silicate glasses (also referred to as AS glasses, aluminosilicate glasses or aluminosilicate glasses), which _{include as components in particular Al 2} O ₃ and SiO ₂ as well as alkali oxides other than lithium oxide Li ₂ O, as well as lithium aluminum Silicate glasses (also referred to as LAS glasses, lithium aluminosilicate glasses or lithium aluminosilicate glasses), which also _{contain Li 2} O as a component.

Further prior art documents can be found in the patent family for US 2019/0152838 A1 , the patent family for US 2013/0122284 A1 and the previously issued US patent US 9,156,724 B2 , the patent family for US 2015/0079400 A1 with the already granted US property right US 9,714,188 B2 , the patent family for US 2015/0099124 A1 and the previously issued US patent US 9,701,574 B2 , the patent family for WO 2019/085422 A1 , the patent family for US 2017/0197869 A1 and the previously issued US patent US 10,131,567 B2 , the patent family for US 2015/0030840 A1 and the already granted US property right US 10,227,253 B2 , the patent family for US 2015/0140325 A1 and the already granted US property right US 10,125,044 B2 , the patent family for US 2015/0118497 A1 and the already granted US property right US 9,822,032 B2 , the family of property rights to US 2012/0135852 A1 and the already granted US property right US 8,796,165 B2 , the family of property rights to US 2015/0147575 A1 and the previously issued US patent US 10,000,410 B2 as well as in the property right family for US 2015/0376050 A1 and the previously issued US patent US 9,783,451 B2 .

These glasses are designed in such a way that they can be chemically tempered. In the context of the present disclosure, a glass which can be chemically tempered is understood to mean a glass which is accessible to an ion exchange process. In such a process, ions of alkali metals are exchanged in a surface layer of a glass article, such as a glass pane. This is done in such a way that a compressive stress zone is now built up in the surface layer, which is achieved by exchanging ions with smaller radii for ions with larger radii. For this purpose, the glass article is immersed in a so-called ion exchange bath, for example a molten salt, the ion exchange bath comprising the ions with the larger ion radii, in particular potassium and / or sodium ions, so that they migrate into the surface layer of the glass article. In exchange for this, ions with smaller ion radii, in particular sodium and / or lithium ions, migrate from the surface layer of the glass article into the ion exchange bath.

This creates a compressive stress zone. This can be described by the characteristic values of the compressive stress, which is also referred to as “compressive stress” or “CS” for short, and the compressive stress depth, which is also referred to as “Depth of Layer” or “DoL” for short. This compressive stress depth DoL is well known to the person skilled in the art and, in the context of the present disclosure, denotes the depth at which the voltage curve passes through zero voltage. In the case of glasses of the LAS type and LABS type, which are accessible to a mixed exchange process, a distinction is made between two different layer depths, the potassium DoL, which describes the depth of the potassium-induced compressive stress, and the sodium DoL, which is also sometimes called DoCL is abbreviated. This sodium DoL describes the depth of the sodium-induced compressive stress. Alternatively or additionally, this thickness DoL can be determined by means of a stress-optical zero crossing measurement method, for example by means of a measuring device with the trade name FSM-6000 or SLP 1000. These measurement methods are based on different physical methods. The FSM measuring device measures the potassium values (K-DoL and CS (0)), SLP measures the sodium parameters CS (30) and DoCL.

Using the measuring device FSM-6000, the compressive stress of the surface and the maximum compressive stress CS of a pane or a pane-shaped glass article can also be determined for aluminosilicate glasses.

In the context of the present disclosure, the terms of wear resistance and strength, unless explicitly stated otherwise, are used largely synonymously as a generic term for the resistance of a material or a product to mechanical attack. In the context of the present disclosure, special strengths, for example the set-drop strength or the flexural strength (also: flexural tensile strength), are understood as subcases of the (overall) strength of a material or product or article. The hardness of a material is also subsumed under the concept of wear resistance in the context of the present disclosure. In the context of the present disclosure, hardness is understood as the mechanical resistance which a material or a product, for example a disk-shaped glass article, opposes to the penetration of another object. The determined hardness value of a material or a product depends, among other things, on the exact type of hardness test carried out. Well-known hardnesses are, for example, the Mohs hardness or the Vickers hardness, the Mohs hardness being a no longer common method of determining hardness. Rather, the Knoop hardness is often specified. Mohs hardness and Knoop hardness are, however, unfavorable hardness determination methods for glasses and glass ceramics, since they are not suitable for taking into account the microelasticity, especially high microelasticity, of the materials being examined, because these methods work with a visual observation of the impression after the impression and based on this the hardness is determined. The so-called Martens hardness, on the other hand, is determined mathematically using the indentation curve. In the context of the present disclosure, hardness is also understood to mean, in particular, the so-called Martens hardness.

It has been shown that the real loads to which a disk-shaped glass article is exposed cannot be adequately described and simulated by an isolated consideration of abrasion, scratch and / or impact loads. Thus, under real conditions, loads actually occur in which, for example, abrasion on a surface with sharp particles can occur, and for example the impact load that occurs when a test object falls on a disk-shaped glass article to determine impact resistance is only partial, if at all , comparable to the load that occurs when a built-in disc-shaped glass article falls on a surface.

In general, it has been shown that the hardness plays an important role when glasses or glass items are used as covers (or cover panels) for mobile electronics. As a rule, the higher the hardness of the glass or the glass article, the higher the scratch resistance.

• - Zum einen können sehr harte, durchsichtige Materialien verwendet werden. Beispielsweise ist der Einsatz von sogenannten „Saphirgläsern“ (Einkristallen aus Korund) bekannt. Diese werden beispielsweise als Lünetten für Uhren verwendet. Solche Materialien verkratzen nur sehr gering, weisen also nur eine geringe Verkratzungsneigung auf. Allerdings sind diese Materialien nur sehr aufwändig zu verarbeiten und sehr spröde. Dies bedeutet allerdings auch, dass bereits bei sehr geringen Oberflächenbeschädigungen Bruch auftreten kann. Mit anderen Worten sind diese sehr harten Materialien zwar kratzfest, so dass erst bei großen Belastungen eine Verkratzung auftritt - diese kann dann allerdings auch sehr schnell zu Materialversagen durch Bruch führen.
• - Eine andere Möglichkeit, die Kratzfestigkeit einer Abdeckscheibe zu erhöhen, besteht darin, Schichten aus einem Hartstoff auf die Abdeckscheibe aufzubringen. In der Regel sind solche Beschichtungen weniger als 2 µm dick, um die optische Auffälligkeit möglichst gering zu halten, und werden mittels üblicher Beschichtungsverfahren, beispielsweise Sputtern, aufgebracht. Der Vorteil eines solchen Vorgehens ist, dass auf diese Weise eine Abdeckscheibe bestehend aus Glas oder umfassend Glas, beispielsweise ein scheibenförmiger Glasartikel, verwendet werden kann. Mit anderen Worten kann also auf diese Weise ein Material für die Abdeckscheibe verwendet werden, welches gut verarbeitbar ist, und wobei dessen im Vergleich mit Hartstoffmaterialien eher geringe Kratzfestigkeit durch eine Beschichtung verbessert werden kann.

In general, there are two approaches to increasing the surface hardness of covers, i.e. cover panes, in order to avoid scratching:

• - On the one hand, very hard, transparent materials can be used. For example, the use of so-called "sapphire glasses" (single crystals made of corundum) is known. These are used, for example, as bezels for watches. Such materials only scratch very little, so they have only a low tendency to scratch. However, these materials are very difficult to process and very brittle. However, this also means that even with very little surface damage, breakage can occur. In other words, these very hard materials are scratch-resistant, so that scratching only occurs when subjected to high loads - but this can also very quickly lead to material failure due to breakage.
• - There is another possibility of increasing the scratch resistance of a cover panel in applying layers of a hard material to the cover plate. As a rule, such coatings are less than 2 μm thick, in order to keep the visual conspicuousness as low as possible, and are applied by means of conventional coating processes, for example sputtering. The advantage of such a procedure is that in this way a cover pane consisting of glass or comprising glass, for example a disk-shaped glass article, can be used. In other words, in this way a material can be used for the cover disk which is easy to process, and its scratch resistance, which is rather low in comparison with hard material, can be improved by a coating.

However, this again has the disadvantage that a complex coating step is necessary. Coating processes which are usually used for applying hard material layers are also not suitable for coating three-dimensionally shaped substrates. The application of the coating to corners and edges of the disk-shaped glass article to be coated is also not possible in this way. Furthermore, the hardness gradient between the disk-shaped glass article and the coating is very steep. This often leads to detachment at the interface between these two materials, especially when exposed to thermal or mechanical loads.

It has now been shown that the plastic or elastic behavior of a material, for example glass, also plays a major role in susceptibility to scratching. Because the scratching introduces temporary tensions into the material, which are absorbed by elastic behavior and can relax without damage after being relieved. However, if the introduced temporary stresses lead to plastic deformation of the material, temporary stresses become permanent stresses which can lead to a reduction in strength, in the worst case to breakage when the load is removed.

There is therefore a need for improved disk-shaped glass articles for use as a cover disk which are sufficiently scratch-resistant, but at the same time have a low degree of brittleness.

Object of the invention

The object of the invention is therefore to provide a disk-shaped glass article, in particular a glass article which is suitable for use as a cover disk and which at least partially alleviates the problems of the prior art.

Summary of the invention

The object is achieved by the subject matter of the independent claims. Preferred and special embodiments are the subject of the dependent claims, the description and the drawings.

According to a first aspect, the present disclosure thus relates to a chemically pre-stressed or at least chemically pre-stressable, disk-shaped glass article. This comprises a glass with a composition comprising Al ₂ O ₃ , SiO ₂ , Li ₂ O and B ₂ O ₃ , the glass and / or the glass article at most 7 wt.% B ₂ O ₃ , preferably at most 5 wt. % B ₂ O ₃ , particularly preferably at most 4.5% by weight B ₂ O ₃ . In other words, the glass or the glass article is made of lithium-aluminum-borosilicate glass (LABS-glass) or lithium-aluminum-borosilicate glass article, although the content of B ₂ O ₃ in the glass and / or glass article is limited.

Such a configuration of a glass article is advantageous. It has been shown that with or from such a LABS glass a glass article can be obtained in a surprisingly simple manner, which can advantageously combine high surface hardness with high pretension and at the same time good mechanical resistance to loads relevant to use, for example a so-called "Sharp impact" can be achieved.

This is all the more surprising since it was previously known that a certain content of B ₂ O ₃ may be suitable for increasing the scratch resistance of a glass or a glass article, but it has also been shown that this effect is limited.

Surprisingly, however, it has been shown that the increase in scratch resistance does not lead to an improvement in the performance properties of a glass article, for example for use as a cover pane. Rather, it has been shown that in the case of LABS glasses there can be a highly advantageous improvement in the mechanical properties, in particular the elastic properties, of the glass or the glass article, in particular also in the pre-stressed state. The reason for this is not fully understood, but the inventors assume that these highly advantageous properties of the glass or the glass article are caused by the content of B ₂ O ₃ in a lithium-aluminum-silicate glass.

For this, it can be preferred that the glass or the glass article has a certain minimum content of B ₂ O ₃ . According to one embodiment, the glass and / or the glass article therefore comprises at least 0.5% by weight B ₂ O ₃ , preferably at least 1.0% by weight B ₂ O ₃ , particularly preferably at least 1.4% by weight B ₂ O ₃ .

• - Der Glasartikel weist in einem Verfahren zur Härteprüfung in Anlehnung an oder gemäß DIN EN ISO 14577 bei Indentierung mit einem Vickers- Indenter einen E*-Modul (auch als Plattenmodul bezeichnet) von höchstens 87 GPa bei einer Indentierungstiefe von 1 µm und/oder einen E*-Modul von höchstens 80 GPa bei einer Indentierungstiefe von 2 µm und/oder einen E*-Modul von höchstens 78 GPa bei einer Indentierungstiefe von 3 µm auf, wobei die Untergrenze für den E*-Modul bevorzugt jeweils bei mindestens 72 GPa liegt.
• - Der Glasartikel weist in einem Verfahren zur Härteprüfung in Anlehnung an oder gemäß DIN EN ISO 14577 bei Indentierung mit einem Vickers-Indenter einen elastischen Anteil der Verformung von wenigstens 58 % bei einer Indentierungstiefe von 1 µm auf.

According to a further aspect, the present disclosure relates to a disk-shaped glass article, in particular a disk-shaped glass article as described above, which has at least one of the following features:

• - In a hardness test method based on or in accordance with DIN EN ISO 14577, when indented with a Vickers indenter, the glass article has an E * module (also known as a plate module) of at most 87 GPa with an indentation depth of 1 µm and / or a E * module of at most 80 GPa at an indentation depth of 2 µm and / or an E * module of at most 78 GPa at an indentation depth of 3 µm, the lower limit for the E * module preferably being at least 72 GPa in each case .
• - In a method for hardness testing based on or in accordance with DIN EN ISO 14577, when indented with a Vickers indenter, the glass article has an elastic portion of the deformation of at least 58% at an indentation depth of 1 μm.

The E * module is the plate module. This is defined as $$\mathrm{E.}*=\frac{{\mathrm{E.}}_{\mathrm{I.}T}}{1-{\nu }_s^2}$$

With: E _IT penetration modulus and v _s Poisson's constant of the sample.

$$E_{\text{IT}}=\frac{1-{\left({\nu }_{\text{s}}\right)}^2}{\frac{1}{E_{\text{r}\text{,n}}}-\frac{1-{\left({\nu }_{\text{i}}\right)}^2}{E_{\text{i}}}}$$

Furthermore, the following definitions of the apply to the E * module and the penetration module E _IT Standard DIN EN ISO 14577-1 $${\mathrm{E.}}^{\ast }=\frac{1}{\frac{1}{{\mathrm{E.}}_{\text{r}\text{, n}}}-\frac{1-\left({\nu }_{\text{i}}^2\right)}{{\mathrm{E.}}_{\text{i}}}}=\frac{{\mathrm{E.}}_{\text{IT}}}{1-\left({\nu }_{\text{s}}^2\right)}$$

$${\mathrm{E.}}_{\text{IT}}=\frac{1-{\left({\nu }_{\text{s}}\right)}^2}{\frac{1}{{\mathrm{E.}}_{\text{r}\text{, n}}}-\frac{1-{\left({\nu }_{\text{i}}\right)}^2}{{\mathrm{E.}}_{\text{i}}}}$$

vs

die Poissonzahl der Probe;

vi

die Poissonzahl des Eindringkörpers (bei Diamant 0,07) (z. B. in Literaturhinweis [6]);

Er

der reduzierte Modul bei Eindringkontakt;

Ei

der Modul des Eindringkörpers (bei Diamant 1 140 GPa) (z. B. in Literaturhinweis [6]);

It is

vs.

the Poisson's ratio of the sample;

vi

the Poisson's ratio of the indenter (0.07 for diamond) (e.g. in reference [6]);

He

the reduced modulus on intrusion contact;

egg

the modulus of the indenter (for diamond 1 140 GPa) (e.g. in reference [6]);

A schematic diagram of an indentation shows 1 . A force is at work here F. on an indenter or indenter 3 . The force acts in the normal direction to the surface 41 a test body or a sample 4th whose hardness is to be determined and is therefore also referred to as normal force. The penetration depth or penetration depth becomes perpendicular to the surface 41 determined, and is in 1 with H respectively. h _p designated.

• Die Indentierung erfolgt mit einem Vickers-Indenter bei einer Normalkraft zwischen 0,1 N und 5 N unter Verwendung des Testgeräts Micro-Combi-Test (MCT) der Firma csm. Indentiert wird bei einer relativen Raumfeuchte zwischen 30% und 50%. Eindrücken und Auswerten erfolgen nach DIN EN ISO 14577 , wobei hierbei beachtlich ist, dass sich die DIN EN ISO 14577 auf Metalle bezieht und eine entsprechende Norm zur Prüfung von Sprödmaterialien nicht vorliegt. Insofern erfolgt die Bestimmung der Martens-Härte analog bzw. in Anlehnung an das in DIN EN ISO 14577 beschriebene Testverfahren für Metalle bzw. duktile Materialien. Für die Bestimmung der Kenngrößen HM (Martenshärte), E* (Plattenmodul) und η (elastischer Anteil) wurden pro Kraftstufe jeweils zehn Eindrücke gesetzt und die Mittelwerte berechnet.

For the hardness test based on or in accordance with DIN EN ISO 14577 it is about the determination of the so-called Martens hardness. This hardness determination is carried out for the glass articles considered in the context of the present disclosure as follows:

• The indentation takes place with a Vickers indenter at a normal force between 0.1 N and 5 N using the Micro-Combi-Test (MCT) test device from csm. Indentation takes place at a relative room humidity between 30% and 50%. Impressions and evaluations take place after DIN EN ISO 14577 , whereby it is noteworthy that the DIN EN ISO 14577 relates to metals and a corresponding standard for testing brittle materials is not available. In this respect, the Martens hardness is determined analogously or based on the in DIN EN ISO 14577 described test procedures for metals or ductile materials. To determine the parameters HM (Martens hardness), E * (plate module) and η (elastic component), ten impressions were made for each force level and the mean values were calculated.

A Vickers indenter is an equilateral diamond pyramid with an opening angle, determined between the side surfaces of the pyramid, of 136 °. The penetration body is also described, for example, in US Pat DIN EN ISO 6507-2 .

Such a design of a glass article is very advantageous because, in a very surprising way, it is possible to achieve particularly good scratch resistance with, at the same time, good resistance of the glass article to so-called sharp-impact loads (for example in a so-called set-drop test).

• Eine Glasscheibe wird auf einer Probenaufnahme fixiert und aus kumulierenden Fallhöhen auf einen definierten Untergrund fallen gelassen. Der im Set-Drop-Test verwendete Glasartikel weist eine Länge von 99 mm und eine Breite von 59 mm auf und wird dargestellt magnetisch mit einem Probendummy in der Probenaufnahme fixiert. Zunächst wird dabei eine Kunststoffplatte mit Hilfe eines doppelseitigen Klebebandes in ein Metallgehäuse, welches Form und Gewicht einer Halterung für ein mobiles Endgerät, beispielsweise ein Smartphone, hat, geklebt. Es eignen sich hierbei beispielsweise Kunststoffplatten mit Dicken zwischen 4,35 mm und bis 4,6 mm. Das Einkleben erfolgt bevorzugt mittels eines doppelseitigen Klebebandes mit einer Dicke von etwa 100 µm. Auf die Kunststoffplatte wird dann mittels eines doppelseitigen Klebebandes, vorzugsweise eines doppelseitigen Klebebandes mit der Dicke 295 µm, insbesondere ein doppelseitiges Klebeband der Marke tesa®, Produktnummer 05338, der zu testende scheibenförmige Glasartikel so aufgeklebt, dass zwischen der Oberkante des Gehäuses bzw. der Halterung und der Oberkante des Glasartikels ein Abstand zwischen 350 µm und 450 µm erhalten wird. Der Glasartikel liegt höher als der Rahmen des Gehäuses und es darf kein direkter Kontakt zwischen Glaskörper und Aluminiumgehäuse auftreten. Das so erhaltene „Set“ mit einem Gewicht von 177,5 g, welches den Einbau eines Glasartikels in ein mobiles Endgerät nachempfindet und eine Art „Dummy“ für ein echtes mobiles Endgerät, hier insbesondere ein Smartphone, ist, wird anschließend auf eine Fläche der Größe DIN A4, die sogenannte Aufprallfläche, mit der Glasseite nach unten mit einer Anfangsgeschwindigkeit in vertikaler Richtung, somit Fallrichtung von Null, fallen gelassen. Die Aufprallfläche wird dabei wie folgt hergestellt: Sandpapier mit einer entsprechenden Körnung, beispielsweise der Körnung 60 (#60), wird mittels eines doppelseitigen Klebebandes, beispielsweise eines Klebebandes der Dicke 100 µm auf eine Bodenplatte geklebt. Als Klebeband wurde tesa® (10m/15mm), transparent, doppelseitig, Produktnummer 05338, genutzt. Die Körnung ist im Rahmen der vorliegenden Offenbarung definiert gemäß den Normen der Federation of European Producers of Abrasives (FEPA), Beispiele dafür siehe auch in DIN ISO 6344 , insbesondere DIN ISO 6344-2:2000-04 , Schleifmittel auf Unterlagen - Korngrößenanalyse - Teil 2: Bestimmung der Korngrößenverteilung der Makrokörnungen P12 bis P220 ( ISO 6344-2:1998 ).

The set-drop test, which is intended to simulate a real application, is preferably carried out as follows:

• A pane of glass is fixed on a sample holder and dropped onto a defined surface from cumulative drop heights. The glass article used in the set-drop test has a length of 99 mm and a width of 59 mm and is shown magnetically fixed in the sample holder with a sample dummy. First, a plastic plate is glued with the help of double-sided adhesive tape in a metal housing, which has the shape and weight of a holder for a mobile device, for example a smartphone. For example, plastic plates with thicknesses between 4.35 mm and up to 4.6 mm are suitable here. Gluing in is preferably carried out by means of a double-sided adhesive tape with a thickness of about 100 μm. The disc-shaped glass article to be tested is then glued to the plastic plate by means of a double-sided adhesive tape, preferably a double-sided adhesive tape with a thickness of 295 µm, in particular a double-sided adhesive tape of the tesa® brand, product number 05338, in such a way that between the upper edge of the housing or the holder and the upper edge of the glass article a distance between 350 µm and 450 µm is obtained. The glass article is higher than the frame of the housing and there must be no direct contact between the glass body and the aluminum housing. The “set” obtained in this way with a weight of 177.5 g, which simulates the installation of a glass article in a mobile device and is a kind of “dummy” for a real mobile device, in particular a smartphone, is then placed on a surface of the Size DIN A4, the so-called impact surface, with the glass side downwards at an initial speed in the vertical direction, i.e. the fall direction of zero. The impact surface is produced as follows: Sandpaper with an appropriate grain size, for example 60 (# 60), is stuck to a base plate by means of double-sided adhesive tape, for example an adhesive tape with a thickness of 100 μm. The adhesive tape used was tesa® (10m / 15mm), transparent, double-sided, product number 05338. In the context of the present disclosure, the grain size is defined in accordance with the standards of the Federation of European Producers of Abrasives (FEPA), for examples see also in DIN ISO 6344 , in particular DIN ISO 6344-2: 2000-04 , Abrasives on backing - Grain size analysis - Part 2: Determination of the grain size distribution of the macro-grain sizes P12 to P220 ( ISO 6344-2: 1998 ).

The base plate must be solid and is preferably made of aluminum or alternatively also of steel, but can also be made as a stone slab and include, for example, granite or marble. The weight of the base plate, which is an aluminum base in the information disclosed here, amounts to approx. 3 kg. The sandpaper must be completely taped and glued on without bubbles. The impact surface may only be used for ten drop tests and must be replaced after the tenth drop test. The sample, i.e. the set obtained, is inserted into the test device and aligned using a 2D spirit level (circular vial) so that the set is stored horizontally, with the disc-shaped glass article pointing to the floor, i.e. in the direction of the impact surface. The first fall is 25 cm, then the fall is from a height of 30 cm. If there is still no break, the height of fall is increased in 10 cm steps until the glass breaks. The height of the fracture, the origin of the fracture and the appearance of the fracture are noted. The test is performed on 15 samples and an average is taken.

It can be advantageous to attach the disk-shaped glass article to the plastic plate in such a way that the disk-shaped glass article remains adhered to a film in the event of a glass break, in order to be removed as easily as possible on the one hand, but also to enable the glass article to be examined . For this purpose, it can be advisable, in addition to the adhesive tapes used, to arrange a self-adhesive film, for example a film such as that used for wrapping books, between the plastic plate and the disc-shaped glass article. The broken, disc-shaped glass article can then be removed by means of this film.

As stated above regarding the state of the art, it has so far been shown that substances commonly referred to as very “hard”, such as Al ₂ O ₃ (which is also referred to as “sapphire” or sapphire glass ”) have a high level of scratch resistance, but at the same time are very brittle, so that they quickly fail due to breakage in a real load case, such as the so-called set-drop test.

By means of a configuration of the glass article according to embodiments, a scratch-resistant glass article can now surprisingly be achieved, which at the same time also has good performance in a test that simulates a real load case, such as the aforementioned set-drop test.

• Getestet wird die Kratzfestigkeit ebenfalls mit dem Gerät Micro-Combi-Test (MCT) der Firma csm. Eine schematische Darstellung des Messprinzips beim Kratzvorgang zeigt 2. Der Kratztest erfolgt mit einem Indenter 3, welcher im Rahmen der vorliegenden Offenbarung als Knoop-Indenter ausgebildet ist, wobei die Normalkraft (hier bezeichnet als F_N ) 4 N beträgt. Der Indenter 3 wird mit einer Geschwindigkeit von 24 mm/min über eine Strecke von 1 mm bewegt, und zwar in Richtung des Pfeils 301.Gleichwertig hierzu kann auch der Knoop-Indenter feststehend ausgebildet sein und relativ zu diesem die Probe 4 bewegt werden Neben der Normalkraft F_N wirkt dabei auf die zu testende Oberfläche 41 der Probe 4 noch die parallel zur Oberfläche 41 wirkende Tangentialkraft F_T . Die Penetrationstiefe (auch Penetrationshöhe, siehe 1, dort bezeichnet als h oder h_p ) wird mittels eines Sensors 31 bestimmt. Das mittels dieses Tests erhaltene Ergebnis ist dabei insbesondere von Material, Größe und Form des Indenters 3 sowie von der Beschaffenheit der getesteten Probe 4 abhängig, beispielsweise vom Material der Probe 4 und/oder dessen Mikrostruktur. Für den Fall, dass die Probe 4 eine Oberflächenschicht 401 aufweist, deren Zusammensetzung und/oder sonstige Beschaffenheit von den Bulkeigenschaften abweicht, beispielsweise in Form einer Beschichtung oder einer Schicht, welche beispielsweise aufgrund eines Ionenaustauschs erhalten wurde, kann das mittels dieses Kratztestes erhaltene Ergebnis auch von der Dicke der Oberflächenschicht 401, deren Zusammensetzung und/oder Mikrostruktur abhängen. Für den Test werden bei einer relativen Luftfeuchtigkeit zwischen 30% und 50% 50 Kratzer 42 nebeneinander auf die Probe 4 aufgebracht bzw. in deren Oberfläche 41 eingebracht, wobei wie ausgeführt der Indenter 3 als Knoop-Indenter ausgebildet ist. Die Auswertung erfolgt als visuelle Beurteilung der Kratzer 42 bzw. Kratzspuren 42 auf Ausmuschelungen 43. Die Anzahl von Kratzern bzw. Kratzspuren 42 mit Ausmuschelungen 43 wird dokumentiert. Eine beispielhafte Darstellung einer guten Probe ohne Ausmuschelungen 43 an der Kratzspur bzw. dem Kratzer 42 ist 3a zu entnehmen. Eine im Sinne dieses Kratztests schlechte Probe mit Ausmuschelungen 43 an der Kratzspur bzw. dem Kratzer 42 zeigen jeweils 3b und 3c. Im Falle der Darstellung der 3b entsteht die Ausmuschelung erst nach dem Beginn der Relativbewegung des Indenters 3 relativ zu dem Probenkörper 4, welches an einer anfänglichen Kratzspur 42 ohne Ausmuschelungen 43 und erst nach Beginn der Relativbewegung eintretenden Ausmuschelungen 43 zu erkennen ist. Im Falle der Darstellung der 3c entsteht die Ausmuschelung bereits mit dem Beginn der Relativbewegung des Indenters 3 relativ zu dem Probenkörper4, welches an dem Fehlen einer alleinigen anfänglichen Kratzspur 42 zu erkennen ist, da bereits mit dem Beginn der Relativbewegung des Indenters 3 relativ zu dem Probenkörper 4 an deren lateralen Breite zu erkennende Ausmuschelungen 43 auftreten, in welchen dann die Kratzspur 42 verläuft.

In the context of the present disclosure, the scratch resistance is preferably determined as follows:

• The scratch resistance is also tested with the Micro-Combi-Test (MCT) device from csm. A schematic representation of the measuring principle during the scratching process is shown 2 . The scratch test is carried out with an indenter 3 , which is designed as a Knoop indenter in the context of the present disclosure, wherein the normal force (referred to here as F _N ) Is 4 N. The indenter 3 is moved at a speed of 24 mm / min over a distance of 1 mm in the direction of the arrow 301 At the same time, the Knoop indenter can also be designed to be stationary and the sample relative to it 4th be moved in addition to the normal force F _N acts on the surface to be tested 41 the sample 4th nor those parallel to the surface 41 acting tangential force F _T . The penetration depth (also penetration height, see 1 , there referred to as H or h _p ) is by means of a sensor 31 certainly. The result obtained by means of this test depends in particular on the material, size and shape of the indenter 3 as well as the nature of the sample tested 4th depending, for example on the material of the sample 4th and / or its microstructure. In the event that the sample 4th a surface layer 401 whose composition and / or other nature deviates from the bulk properties, for example in the form of a coating or a layer which was obtained, for example, due to an ion exchange, the result obtained by means of this scratch test can also depend on the thickness of the surface layer 401 whose composition and / or microstructure depend. For the test, there are 50 scratches at a relative humidity between 30% and 50% 42 side by side to the test 4th applied or in their surface 41 introduced, with the indenter as stated 3 is designed as a Knoop indenter. The evaluation takes place as a visual assessment of the scratches 42 or scratch marks 42 on mussels 43 . The number of scratches or scratch marks 42 with mussels 43 is documented. An exemplary representation of a good sample without mussels 43 at the scratch mark or the scratch 42 is 3a refer to. In terms of this scratch test, a bad sample with mussels 43 at the scratch mark or the scratch 42 show each 3b and 3c . In the case of the representation of the 3b the shell does not arise until after the start of the relative movement of the indenter 3 relative to the specimen 4th which is at an initial scratch mark 42 without mussels 43 and scallops that occur only after the start of the relative movement 43 can be seen. In the case of the representation of the 3c the shell is created with the beginning of the relative movement of the indenter 3 relative to the specimen 4, which is due to the lack of a single initial scratch mark 42 it can be seen that with the beginning of the relative movement of the indenter 3 relative to the specimen 4th scallops recognizable by their lateral width 43 occur in which then the scratch mark 42 runs.

A widening of the scratch track or the scratch by at least three times the lateral width of the initial scratch track in the surface is used as a shell 41 and in the extension parallel to the surface 41 as well as perpendicular to the scratch track, thus perpendicular to the direction of the arrow 301 viewed. Should a scallop-out occur at the beginning of the movement of the indenter or the test body 4th arise, will be at least three times the value of the lateral width of the indenter as the shell 3 when it has penetrated the glass in the plane of the surface 41 of the test body 4th Understood.

A Knoop indenter is a diamond tip with a rhombic shape. The penetrator (or indenter) is for example in the DIN EN ISO 4545 described.

Surprisingly, a result of 0 can be achieved with glasses or glass articles according to embodiments (for example a glass or a glass article with which the total of measured values 25th is obtained, see 4th until 6th ), ie none of the scratches or scratch marks caused scallops. This is all the more surprising as comparative samples on glass articles which comprise a glass of a different composition or which have a different physical behavior when indented can have between 30 and 50 scratches with scallops (e.g. a glass or a glass article with which the total of the measured values 23 respectively. 24 is obtained, see 4th until 6th ).

The inventors assume that this very surprisingly good scratch resistance can be achieved by a combination of suitable prestressing parameters, that is to say, in particular, can also be represented as a result of the prestressing introduced into a glass article.

The present disclosure therefore also relates to a disk-shaped glass article, preferably a disk-shaped glass article according to embodiments of the disclosure, having a bias, preferably obtained by at least one ion exchange, in which, together with the introduction of the bias, an elastic component η of the deformation up to a depth of approximately 3 µm is increased.

The special feature of the glass article according to the present disclosure can therefore be seen in the fact that the glass article has special elastic properties in a near-surface area, in particular a near-surface area up to about 3 μm, in particular up to about 2 μm and even at a depth of about 1 µm. Because here, for example, a particularly high elastic component is shown in a method for hardness testing based on or in accordance with DIN EN ISO 14577 of at least 58%.

Although glasses are known in which even higher elastic proportions can be achieved, these have a different structure and, in particular, cannot be chemically toughened to the same extent as preferred glasses or glass articles according to embodiments. The inventors suspect that the particularly good properties of the glass or glass article could be attributed to the present disclosure to the specific glass structure in which a certain proportion of B ₂ O ₃ vorliegt.B ₂ O ₃ is often different than, for example, SiO ₂ , no or at least less three-dimensional links, but rather tends towards two-dimensional linked structures, which for the sake of clarity can also be compared with the two-dimensional structures of graphite. It is therefore assumed that a glass structure can be obtained through the certain, albeit small, share of the network image B ₂ O ₃ in the glass or glass article, in which the borate glass structures can at least support a kind of sliding effect in the glass network, so that at least in a surface near Increased elasticity can be observed in the area.

According to one embodiment of the glass article, the glass and / or the glass article comprises at most 3% by weight P ₂ O ₅ , preferably at most 2% by weight P ₂ O ₅ and particularly preferably at most 1.7% by weight P ₂ O ₅ . P ₂ O ₅ is an optional component of the glass or the glass article according to the present disclosure. P ₂ O ₅ is a glass component which forms a network and can increase the meltability of a glass. P ₂ O ₅ can also facilitate the ion exchange, that is to say lead to shorter process times. The content of the glass or glass article is preferably at least 0.1% by weight, preferably at least 0.25% by weight and particularly preferably at least 0.5% by weight. However, too high a content of P ₂ O ₅ in a glass or glass article can reduce the chemical stability of the glass or glass article, or P ₂ O ₅ can cause segregation phenomena. P ₂ O ₅ can also lead to difficulties in production, since the material of the melting unit can be attacked. The phosphate content is therefore preferably limited and according to the present disclosure is at most 3% by weight P ₂ O ₅ , preferably at most 2% by weight, particularly preferably at most 1.7% by weight, in the glass or glass article.

It has also been shown, surprisingly, that the combination of components B ₂ O ₃ and P ₂ O ₅ , in particular in the above-mentioned contents, enables a particularly advantageous design of a scratch-resistant and at the same time highly pre-stressed glass article. Here, P ₂ O ₅ can compensate for the negative effects of B ₂ O _{3 on the prestressing properties.} If, for example, a B ₂ O ₃ content is selected that results in B ₂ O _{3 being present in a} trigonal manner in the glass, then this leads to a higher scratch resistance due to the presumably existing slip planes, similar to the structure of graphite. However, if there is a sufficiently high proportion of alkalis and alkaline earths in the overall system that B ₂ O _{3 is} also present in tetragonal form, it particularly binds the alkalis that are decisive for ion exchange more strongly to itself. This results in a more difficult ion exchange. A certain proportion of P ₂ O ₅ can help here, since P ₂ O ₅ forms chains in the glass and thus presumably provides channels in the glass which, viewed as a whole, can facilitate the ion exchange.

In order to create a pre-tension at least in the near-surface area of the glass article up to 3 µm, in particular up to 2 µm and especially up to 1 µm depth, it is also advantageous if the glass or if the glass article has a certain minimum Na ₂ O content. Na ₂ O is a network converter and can therefore, in particular, influence the exchangeability and consequently the pretensioning and, accordingly, also the achievable or achieved pretensioning of a glass article. According to one embodiment, the glass and / or the glass article comprises at least 0.8% by weight Na ₂ O, with the glass and / or the glass article preferably at most 8% by weight Na ₂ O, preferably at most 7.5% by weight. -% Na ₂ O and particularly preferably at most 7% by weight Na ₂ O comprises. In other words, according to this embodiment, the glass and / or the glass article is designed as a glass or glass article comprising _{Na 2 O.} It is advantageous if the glass and / or the glass _{article comprises Na 2} O, because in this case an ion exchange of sodium ions for potassium ions is possible. With regard to the mechanical properties, this can lead to particularly advantageous configurations of a glass article.

In particular, it has been shown that the interaction of the glass components, in particular the component B ₂ O ₃ with Na ₂ O, enables a particularly advantageous configuration of the glass article. As a network converter, Na ₂ O influences the properties of the glass article also in its interface. As stated above, Na ₂ O also enables interchangeability with respect to Potassium ions. This means that the area of the glass article close to the surface can be designed in this way in such a way that sodium is exchanged for potassium in the area close to the surface. It is precisely in this area close to the surface that the good, highly advantageous elastic properties of the glass article are achieved, which in particular also lead or can lead to the very good scratch results explained above with only very little, in some cases even no scalping of glass articles according to embodiments.

The good mechanical, in particular elastic, properties of the glass article according to the present disclosure can advantageously be supported by a certain content of K ₂ O in the glass and / or the glass article. According to one embodiment, the glass and / or the glass article comprises at most 1% by weight K ₂ O, preferably up to 0.8% by weight K ₂ O and particularly preferably up to 0.7% by weight K ₂ O, with particular preferably the glass and / or the glass article comprises _{at least 0.1% by weight of K 2 O.} For the setting of optimized mechanical properties, in particular an improved wear resistance, of a glass or a glass article, in particular an optimized sharp impact strength with at the same time good pretensioning and improved scratch resistance, it can be advantageous if the glass contains a certain amount of K ₂ O includes. In particular, it has been shown that the ion exchange and thus the biasability can be improved _{by K 2 O.} This is attributed to the glass structure loosened up by the potassium ions. Furthermore, K ₂ O improves the meltability of the glass. According to the present disclosure, the glass or the glass article preferably comprises at least 0.1% by weight of K ₂ O, particularly preferably at least 0.2% by weight

Li ₂ O is a necessary component of the glasses and glass articles of the present disclosure. In particular, due to the content of lithium oxide in the glasses and / or glass articles according to the present disclosure, both a good strength of tempered glasses in static strength tests such as the flexural strength after four-point bending or in the strength after determination in a double ring test, as well as against blunt- impact loads, such as the ball drop test, as well as sharp-impact loads, i.e. the action on the surface of a glass or a glass article with particles that have an angle of less than 100 ° (which, for example, also in a so-called set -Drop test can be shown). The glasses and / or glass articles according to the present disclosure are also distinguished by an improved hardness, which is visible, for example, in a method for hardness testing to determine the so-called Martens hardness. Lithium oxide is advantageous because it enables an ion exchange for sodium and thus leads to a high degree of pretensioning or pretensioning of the glass or glass article. The glasses and / or glass articles according to the present disclosure therefore comprise Li ₂ O to an extent of at least 3% by weight, preferably at least 3.5% by weight. However, the content of Li ₂ O is limited according to the present disclosure. For example, if the Li ₂ O content is too high, segregation can occur. The glasses and glass articles therefore contain Li ₂ O to a maximum of 5.5% by weight.

It is advantageous to ensure a certain minimum proportion of SiO ₂ in the glass or glass article in order to improve the chemical resistance and also the mechanical properties of the glass or the glass article. The latter is attributed to the support of the formation of a rigid, rigid basic glass network that, in the event of an ion exchange, does not relax much and can thus enable a high bias. However, glasses having too high a proportion of SiO ₂ to a melting process with subsequent heat forming, due to the extremely high melting temperatures of pure SiO ₂ is not commercially available. Furthermore, too high a proportion of SiO ₂ can lead to increased brittleness of the glass or the glass article, so that for these reasons the proportion of SiO ₂ must be limited.

It is therefore advantageous if the glass or if the glass article _{comprises sufficient SiO 2} to enable sufficient pretensioning or pretensioning. According to one embodiment, the glass or the glass article therefore comprises at least 57% by weight SiO ₂ , preferably at least 59% by weight SiO ₂ and particularly preferably at least 61% by weight SiO ₂ . The content of SiO ₂ in the glass or glass article is preferably limited, however, in order to avoid the result that the glass or glass article becomes too brittle. According to one embodiment, the glass or the glass article preferably comprises at most 69% by weight SiO ₂ , preferably at most 67% by weight.

Al ₂ O ₃ is a known network former in glasses with a sufficiently high alkali content, which is added in particular to alkali-containing silicate glasses. The addition of Al ₂ O ₃ reduces the number of oxygen at the point of separation so that, despite a certain content, a rigid network can be obtained, which is advantageous for the development of good pretensioning properties. In addition, Al ₂ O ₃ facilitates the ion exchange. In this way, the temperability of an alkali-containing silicate glass can be improved, so that a particularly highly tempered glass article can be obtained with such a glass. Of the According to one embodiment, the minimum content of Al ₂ O ₃ in the glass is therefore advantageously 17% by weight. However, too high an Al ₂ O ₃ content reduces the chemical resistance of the resulting glass or glass article, in particular the acid resistance, and also increases the melting temperature. It is also advantageous for the formation of a glass article which also shows good performance in practical applications, for example high surface hardness and / or good scratch resistance, if the glass network is not too rigid, but still flexible or has elastic components. The content of Al ₂ O ₃ in the glass or glass article is therefore preferably limited according to further embodiments and is preferably at most 25% by weight, particularly preferably at most 21% by weight.

The sum of the Al ₂ O ₃ and SiO ₂ content, based on the information in% by weight, is preferably between at least 75 and at most 92, preferably at most 90, and / or is the total content of network formers in the glass and / or Glass articles not more than 92% by weight, particularly preferably not more than 90% by weight.

A content of the network _{formers Al 2} O ₃ and SiO ₂ of at least 75% by weight is particularly advantageous because a sufficient amount of glass formers is present in this way. In other words, it is ensured in this way that a vitreous material is obtained and the risk of devitrification during the manufacture of the glass or glass article is reduced. On the other hand, the content of the aforementioned network formers should not be too high, because otherwise the resulting glass can no longer be easily melted. Therefore, the content of Al ₂ O ₃ and SiO _{2 is} preferably limited and is not more than 92% by weight, preferably not more than 90% by weight. The total content of network formers in the glass or glass article is preferably not more than 92% by weight, particularly preferably not more than 90% by weight.

According to a further embodiment, the thickness of the glass article is at least 0.4 mm and at most 3 mm.

The thickness of the glass article is preferably at least 0.5 mm.

The thickness of the glass article is furthermore preferably limited and, according to one embodiment, is at most 2 mm, preferably at most 1 mm.

Another aspect of the present disclosure relates to a lithium-aluminum-borosilicate glass, comprising the following components in% by weight: SiO ₂ 57 to 69, preferably 59 to 69, particularly preferably 61 to 69, whereby the upper limit can preferably be 67 in each case, Al ₂ O ₃ 17 to 25, preferably 17 to 21, B ₂ O ₃ 0.5 to 7, preferably 0.5 to 5, particularly preferably 0.5 to 4.5, the lower limit preferably being 1.0% by weight of B ₂ O ₃ in each case, particularly preferably at least 1 in each case, 4% by weight B ₂ O ₃ , Li ₂ O 3 to 5.5, preferably 3.5 to 5.5, Na ₂ O 0.8 to 8, preferably 0.8 to 7.5, particularly preferably 0.8 to 7 where the sum of the Al ₂ O ₃ and SiO ₂ content, based on the information in% by weight, is preferably between at least 75 and at most 92, preferably at most 90.

Such a glass is advantageous because it is designed to be chemically tempered in such a way that chemically tempered glass articles with a particularly high strength in the so-called set-drop test are obtained even when using coarse grain sizes, for example 60 grain sizes. At the same time, the above-described advantageous surface hardness and / or scratch resistance of glass articles are achieved, since the glass is designed in such a way that it has a high elastic component, at least in the case of deformations or indentations in a surface layer. The glass according to the present disclosure is still surprisingly easy to melt despite a high content of glass formers, here particularly preferably a high content of the glass formers SiO ₂ and Al ₂ O ₃ of at least 75% by weight.

According to the inventors, the advantageous properties of the glass or the glass article according to embodiments of the present disclosure can possibly be attributed to the fact that a glass of the composition is designed so that it can be toughened within the above-mentioned limits that a chemically highly toughened glass article can be obtained which nevertheless, most surprisingly, it is elastically deformable at least to a certain extent in the event of deformation and therefore less to brittle fracture or to scalloping when the surface is exposed to scratches, this tends to be the case with known hard materials such as Al ₂ O ₃ .

According to one embodiment of the lithium-aluminum-borosilicate glass, this is given by the following composition in% by weight: SiO ₂ 57 to 69, preferably 59 to 69, particularly preferably 61 to 69, whereby the upper limit can preferably be 67 in each case, Al ₂ O ₃ 17 to 25, preferably 17 to 21, B ₂ O ₃ 0.5 to 7, preferably 0.5 to 5, particularly preferably 0.5 to 4.5, the lower limit preferably being 1.0% by weight of B ₂ O ₃ in each case, particularly preferably at least 1 in each case, 4% by weight B ₂ O ₃ , Li ₂ O 3 to 5.5, preferably 3.5 to 5.5, Na ₂ O 0.8 to 8, preferably 0.8 to 7.5, particularly preferably 0.8 to 7 K ₂ O 0 to 1, preferably 0 to 0.8, particularly preferably 0 to 0.7 MgO 0 to 2, preferably 0 to 1.5, particularly preferably 0 to 1, CaO 0 to 4.5, SrO 0 to 2, preferably 0 to 1.5, particularly preferably 0 to 1, ZnO 0 to 3, preferably 0 to 2, particularly preferably 0 to 1.5, P ₂ O ₅ 0 to 3, preferably 0 to 2, particularly preferably 0 to 1.7, ZrO ₂ 0 to 3, preferably 0-2.7, particularly preferably 0 to 2, furthermore, impurities and / or refining agents and / or coloring constituents can be contained in amounts of up to 2% by weight.

ZrO ₂ has the advantage that if the proportion of alkalis in the SiO ₂ network is sufficiently high it builds into the SiO 2 network as a glass former and contributes to the strengthening of the network. In addition to chemical resistance, it also improves mechanical properties. Furthermore, a certain proportion of B ₂ O ₃ leads to a stabilization of the ZrO ₂ in the glass or prevents the formation of ZrO ₂ crystals.

In embodiments, the glass of the glass article can contain ZrO ₂ and particularly preferably comprises a ZrO ₂ content of at least 0.2% by weight as the lower limit.

• - einen lonenaustausch in einem Tauschbad umfassend zwischen mindestens 20 Gew.-%, und bis zu 100 Gew.-% eines Natriumsalzes, vorzugsweise Natriumnitrat NaNO₃, für eine Dauer von mindestens 2 Stunden, bevorzugt mindestens 4 Stunden, und höchstens 24 Stunden bei einer Temperatur zwischen mindestens 380°C und höchstens 440°C, wobei optional ein Kaliumsalz, insbesondere Kaliumnitrat KNO₃, dem Tauschbad zugesetzt werden kann, insbesondere in der Form, dass die Summe des Gehalts von Natriumsalz und Kaliumsalz sich zu 100 % addieren,
• - sowie optional einen zweiten lonenaustausch in einem Tauschbad umfassend zwischen 0 Gew.-% und 10 Gew.-% eines Natriumsalzes, vorzugsweise Natriumnitrat NaNO₃, bezogen auf die Gesamtmenge des Salzes, für eine Dauer von mindestens einer Stunde und höchstens 6 Stunden bei einer Temperatur des Tauschbades von mindestens 380°C und höchstens 440°C, wobei dem Tauschbad ein Kaliumsalz, insbesondere bevorzugt Kaliumnitrat KNO₃ zugesetzt wird, insbesondere in der Form, dass die Summe des Gehalts von Natriumsalz und Kaliumsalz sich zu 100 Gew.- % addieren,
• - sowie optional einen oder mehrere weitere lonenaustauschschritte.

Yet another aspect of the present disclosure relates to a method by which a glass article can be manufactured or manufactured according to the embodiments disclosed herein, comprising the steps:

• - An ion exchange in an exchange bath comprising between at least 20% by weight and up to 100% by weight of a sodium salt, preferably sodium nitrate NaNO ₃ , for a period of at least 2 hours, preferably at least 4 hours, and at most 24 hours for one Temperature between at least 380 ° C and at most 440 ° C, with a potassium salt, in particular potassium nitrate KNO ₃ , optionally being added to the exchange bath, in particular in such a way that the sum of the sodium salt and potassium salt content add up to 100%,
• - and optionally a second ion exchange in an exchange bath comprising between 0% by weight and 10% by weight of a sodium salt, preferably sodium nitrate NaNO ₃ , based on the total amount of the salt, for a period of at least one hour and at most 6 hours for one Temperature of the exchange bath of at least 380 ° C and at most 440 ° C, with a potassium salt, particularly preferably potassium nitrate KNO _{3, being} added to the exchange bath, in particular in the form that the sum of the sodium salt and potassium salt content add up to 100% by weight ,
• - and optionally one or more further ion exchange steps.

Examples

As comparison glasses which have no B ₂ O ₃ in their composition and also do not have the values of the elastic component η discussed in greater detail below, the reference symbol is used 23 provided with a soda-lime glass as well as with the reference number 24 provide a Li-Al-Si glass, in particular a lithium-aluminum-silicate glass with a Li ₂ O content of 4.6% by weight to 5.4% by weight and an Na ₂ O content of 8, 1% by weight to 9.7% by weight and an Al ₂ O ₃ content of 16% by weight to 20% by weight.

The one with the reference number 21 , 22nd and 25th The provided glass article each comprises a lithium-aluminum-borosilicate glass or consists of this glass, containing the following components in% by weight: SiO ₂ 57 to 69, preferably 59 to 69, particularly preferably 61 to 69, whereby the upper limit can preferably be 67 in each case, Al ₂ O ₃ 17 to 25, preferably 17 to 21, B ₂ O ₃ 0.5 to 7, preferably 0.5 to 5, particularly preferably 0.5 to 4.5, the lower limit preferably being 1.0% by weight of B ₂ O ₃ in each case, particularly preferably at least 1 in each case, 4% by weight B ₂ O ₃ , Li ₂ O 3 to 5.5, preferably 3.5 to 5.5, Na ₂ O 0.8 to 8, preferably 0.8 to 7.5, particularly preferably 0.8 to 7 where the sum of the Al ₂ O ₃ and SiO ₂ content, based on the information in% by weight, is preferably between at least 75 and at most 92, preferably at most 90.

The one with the reference number 21 provided glass article has a B ₂ O ₃ content of 3.6% by weight +/- 0.5% by weight.

The one with the reference number 22nd provided glass article has a B ₂ O ₃ content of 3.9% by weight +/- 0.5% by weight.

The one with the reference number 25th provided glass article has a B ₂ O ₃ content of 2.8% by weight +/- 0.5% by weight.

• - einem lonenaustausch in einem Tauschbad umfassend zwischen mindestens 20 Gew.-%, und bis zu 100 Gew.-% eines Natriumsalzes, vorzugsweise Natriumnitrat NaNO₃, für eine Dauer von mindestens 2 Stunden, bevorzugt mindestens 4 Stunden, und höchstens 24 Stunden bei einer Temperatur zwischen mindestens 380°C und höchstens 440°C, wobei optional ein Kaliumsalz, insbesondere Kaliumnitrat KNO₃, dem Tauschbad zugesetzt werden kann, insbesondere in der Form, dass die Summe des Gehalts von Natriumsalz und Kaliumsalz sich zu 100 Gew.-% addieren,
• - sowie optional einem zweiten lonenaustausch in einem Tauschbad umfassend zwischen 0 Gew.-% und 10 Gew.-% eines Natriumsalzes, vorzugsweise Natriumnitrat NaNO₃, bezogen auf die Gesamtmenge des Salzes, für eine Dauer von mindestens einer Stunde und höchstens 6 Stunden bei einer Temperatur des Tauschbades von mindestens 380°C und höchstens 440°C, wobei dem Tauschbad ein Kaliumsalz, insbesondere bevorzugt Kaliumnitrat KNO₃ zugesetzt wird, insbesondere in der Form, dass die Summe des Gehalts von Natriumsalz und Kaliumsalz sich zu 100 Gew.-% addieren,
• - sowie optional einem oder mehreren weiteren lonenaustauschschritten

bis zu einer Tiefe von etwa 4 µm erhaltener, erhöhter elastischer Anteil η der Verformung bei einer Härteprüfung in Abhängigkeit von der Indentierungstiefe, wie dieses nachfolgend noch detaillierter unter Bezugnahme auf 6 beschrieben wird.It is particularly advantageous and surprising with these glasses 21 , 22nd and 25th their by a suitable biasing process, for example

• - An ion exchange in an exchange bath comprising between at least 20% by weight and up to 100% by weight of a sodium salt, preferably sodium nitrate NaNO ₃ , for a period of at least 2 hours, preferably at least 4 hours, and at most 24 hours for one Temperature between at least 380 ° C and at most 440 ° C, with a potassium salt, in particular potassium nitrate KNO ₃ , optionally being added to the exchange bath, in particular in such a way that the sum of the sodium salt and potassium salt content add up to 100% by weight ,
• - and optionally a second ion exchange in an exchange bath comprising between 0% by weight and 10% by weight of a sodium salt, preferably sodium nitrate NaNO ₃ , based on the total amount of the salt, for a period of at least one hour and at most 6 hours for one Temperature of the exchange bath of at least 380 ° C and at most 440 ° C, with a potassium salt, particularly preferably potassium nitrate KNO _{3, being} added to the exchange bath, in particular in the form that the sum of the sodium salt and potassium salt content add up to 100% by weight ,
• - and optionally one or more further ion exchange steps

Increased elastic portion η of the deformation obtained up to a depth of approximately 4 μm in a hardness test as a function of the indentation depth, as will be described in more detail below with reference to FIG 6th is described.

Another advantageous embodiment of a presently disclosed glass has the following composition in% by weight: SiO ₂ 66.2 Al ₂ O ₃ 18.5 B ₂ O ₃ 3.0 Li ₂ O 4.0 Na ₂ O 1.7 K2O 0.3 MgO 0.0 CaO 4.0 SrO 0.0 ZnO 0.0 P ₂ O ₅ 1.1 ZrO ₂ 0.3

Refining agents and / or coloring constituents, such as CeO ₂ , SnO ₂ , Fe ₂ O ₃ , Cl, F, SO _{3, can be contained} in amounts up to a total of 0.7% by weight.

This glass, determined as described above, has a modulus of elasticity of 78 GPa Vickers hardness HV of 594 and a Martens hardness HM of 3640 MPa.

The scratch defects in this glass were 0 (cv), which shows that essentially no scallops occurred in the scratch tests described above.

Yet another advantageous embodiment of a presently disclosed glass has the following composition in% by weight: SiO ₂ 66.8 Al ₂ O ₃ 18.0 B ₂ O ₃ 4.0 Li ₂ O 3.7 Na ₂ O 2.2 K ₂ O 0, 3 MgO 0, 7 CaO 2.5 SrO 0.4 ZnO 0.1 P ₂ O ₅ 0.6 ZrO ₂ 0.0

In this yet further embodiment, too, refining agents and / or coloring constituents, such as CeO ₂ , SnO ₂ , Fe ₂ O ₃ , Cl, F, SO _{3, can be contained} in amounts up to a total of 0.7% by weight.

This glass, determined as described above, has a modulus of elasticity of 82 GPa, a Vickers hardness HV of 572 and a Martens hardness HM of 3989 MPa.

With this glass, too, the scratch defects were at 0 (cv), which shows that essentially no scallops occurred in the scratch tests described above.

Figure list

• 1 eine Prinzipskizze des Indentierens,
• 2 eine schematische Darstellung des Messprinzips beim Kratzvorgang,
• 3a eine beispielhafte Darstellung eines „guten“ Ergebnisses des Kratztests,
• 3b eine beispielhafte Darstellung eines „schlechten“ Ergebnisses des Kratztests, bei welchem die Ausmuschelung erst nach dem Beginn der Relativbewegung des Indenters relativ zu dem Probenkörper zu erkennen ist,
• 3c eine beispielhafte Darstellung eines „schlechten“ Ergebnisses des Kratztests, bei welchem die Ausmuschelung bereits mit dem Beginn der Relativbewegung des Indenters relativ zu dem Probenkörper zu erkennen ist,
• 4 die Darstellung von Messergebnissen der Härteprüfung für unterschiedliche Gläser bzw. Glasartikel,
• 5 den Plattenmodul E* in Abhängigkeit von der Tiefe der Indentierung für unterschiedliche Gläser bzw. Glasartikel,
• 6 den elastischen Anteil der Verformung bei einer Härteprüfung in Abhängigkeit von der Indentierungstiefe für unterschiedliche Gläser bzw. Glasartikel,
• 7 eine schematische und nicht maßstabsgetreue Darstellung eines Glasartikels nach einer Ausführung, sowie
• 8 eine schematische und nicht maßstabsgetreue Schnittdarstellung durch einen Glasartikel nach einer Ausführungsform.

The invention is explained further below with reference to figures. Show it:

• 1 a basic sketch of the indentation,
• 2 a schematic representation of the measuring principle during the scratching process,
• 3a an exemplary representation of a "good" result of the scratch test,
• 3b an exemplary representation of a "bad" result of the scratch test, in which the shell can only be recognized after the start of the relative movement of the indenter relative to the specimen,
• 3c an exemplary representation of a "bad" result of the scratch test, in which the scallop can already be recognized with the start of the relative movement of the indenter relative to the specimen,
• 4th the presentation of measurement results of the hardness test for different glasses or glass articles,
• 5 the plate module E * depending on the depth of the indentation for different glasses or glass articles,
• 6th the elastic portion of the deformation during a hardness test depending on the indentation depth for different glasses or glass articles,
• 7th a schematic and not to scale representation of a glass article according to an embodiment, and
• 8th a schematic and not to scale sectional view through a glass article according to an embodiment.

4th shows the Martens hardness (HM) in MPa determined on five different chemically toughened glass articles, the five different glass articles each having a different glass composition. Different data points can be assigned to these five different glass articles, the data points for the first glass article in 4th as well as in the following 5 and 6th are each designated with a rhombus, for the second glass article each with a circle, for the third glass article with a triangle, the fourth glass article each with a square and for the fifth glass article each with a cross. In the 4th until 6th are these different measured values or, if applicable, corresponding connection or data lines obtained for these data points between these measured values 21 for the first glass item (diamond), 22nd for the second glass item (circle), 23 for the third glass item (triangle), 24 for the fourth glass article (square) and 25th for the fifth glass article (cross). The measured values (or sets of measured values) 21 , 22nd and 25th were obtained for glasses or glass articles according to the present disclosure. The measured values or sets of measured values or data lines 23 and 24 are obtained for comparative examples. The third comparative example corresponds to a conventional soda-lime glass.

For the in 4th The measured values of the Martens hardness shown are obtained by comparing the values obtained for the different glasses or glass articles Measured values that the Martens hardness for the first, second and fifth glass article (corresponding to measured values or curves 21 , 22nd and 25th ) can be higher by up to 25% after their suitable prestressing, as already mentioned above, in particular for indentation depths of, for example, up to about 4 μm. A particularly high Martens hardness can be achieved in particular in the interaction of a suitable glass composition and a suitable tempering process.

The increase in the hardness values is correlated with an increase in the modulus of elasticity or plate modulus E *. This is exemplified by the illustration in 5 . The measured values that are obtained for the respective glasses or glass articles, as well as a corresponding connecting line through these measuring points, are given here.

In general, the hardness in a glass system is correlated with the modulus of elasticity. A higher modulus of elasticity leads to higher local stresses at crack tips for a given load. When scratching with a hard material, the higher modulus of elasticity leads to increased stress on the material. The ion exchange results in a continuous drop in hardness and modulus of elasticity from the surface towards the center. This continuous decrease avoids interfaces at which stress concentrations can arise. On the other hand, the material can be efficiently processed mechanically by grinding and polishing prior to hardening by ion exchange.

The glasses or glass articles according to the invention for which the measured values or data or connecting lines 21 , 22nd and 25th result, surprisingly, with a similar increase in hardness as the comparative examples, those for measured values or connecting lines 23 and 24 obtained, results in a smaller increase in the measured plate modulus. The effect is for the glass or the glass article, which the measured values 21 is assigned, most pronounced. This is related to the special structure of the LABS glass for which the tempering process has been optimized.

The glasses or glass articles according to the invention (see measured values 21 , 22nd and 25th ) also surprisingly have a significantly higher elastic component η
than the soda-lime glass (readings 23 ) and the fourth glass of the LAS glass family or the fourth glass article (measured values 24 ) on how 6th can be found. The LABS glass family has similar values 21 , 22nd , 25th among each other, which are clearly differentiated from the measured values 23 and 24 , the comparative examples.

The elastic component also correlates with the hardness. The combination of hardness, a relatively low modulus of elasticity or, in this case, a plate module (E * module) and a relatively high elastic component η leads to a significant improvement in the scratching behavior in the near-surface areas of the chemically toughened glass article.

7th is the schematic and not to scale representation of a disk-shaped glass article according to the presently disclosed embodiments.

8th shows a schematic and not to scale sectional illustration of a glass article 1 according to the presently disclosed embodiments. The glass article 1 has two zones arranged on the two main surfaces of the glass article 101 which are under compressive stress and are also referred to as compressive stress zones. These compressive stress zones 101 also have them in 2 schematically drawn dimension designated as 41 " DoL ". It is possible that the DoL differs in size on the two sides of the disc-shaped glass article, but these differences are usually within the scope of the measurement accuracy, so that the DoL for a disc-shaped glass article 1 is usually the same on both sides - at least within the scope of the measurement accuracy.

Between the compressive stress zones 101 lies the area 102 , which is under tension.

List of reference symbols

1

Glass articles

101

102

21, 22, 23, 24, 25

Entities of measured values or data lines obtained by means of these

3

Indenter

31

sensor

301

Direction of movement from 3

4th

Sample, specimen

41

Surface to be tested of specimen or sample 4

42

Scratches, scratch marks

43

Scallop

401

Surface layer of sample or test piece 4

F, FN

Force, normal force

FT

Tangential force

h, hP

Penetration depth / height

DoL

Depth of Layer, compressive stress depth

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

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Claims (14)

Chemically toughened or chemically toughenable, disk-shaped glass article (1) comprising a glass with a composition comprising Al ₂ O ₃ , SiO ₂ , Li ₂ O and B ₂ O ₃ , the glass and / or the glass article (1) at most 7 wt. -% B ₂ O ₃ , preferably at most 5% by weight B ₂ O ₃ , particularly preferably at most 4.5% by weight B ₂ O ₃ . Disc-shaped glass article (1) according to Claim 1 , the glass and / or the glass article (1) _{comprising at least 0.5% by weight of B 2} O ₃ , preferably at least 1.0% by weight of B ₂ O ₃ , particularly preferably at least 1.4% by weight B ₂ O ₃ . Disc-shaped glass article (1), in particular according to one of the Claims 1 or 2 , having at least one of the following features: - In a method for hardness testing based on or in accordance with DIN EN ISO 14577 when indenting with a Vickers indenter, the glass article (1) has an E * module of at most 87 GPa with an indentation depth of 1 µm and / or an E * module of at most 80 GPa at an indentation depth of 2 µm and / or an E * module of at most 78 GPa at an indentation depth of 3 µm, the lower limit for the E * module being preferred in each case is at least 72 GPa, - The glass article (1) preferably has an elastic portion of the deformation of at least 58% with an indentation depth of 1 µm in a method for hardness testing based on or according to DIN EN ISO 14577 when indenting with a Vickers indenter on. Disc-shaped glass article (1), in particular according to one of the Claims 1 until 3 , having a bias, preferably obtained by at least one ion exchange, in which, together with the introduction of the bias, an elastic component η of the deformation is also increased to a depth of about 3 μm. Disc-shaped glass article (1) according to one of the Claims 1 until 4th wherein the glass and / or the glass article comprises at most 3% by weight P ₂ O ₅ , preferably at most 2% by weight P ₂ O ₅ and particularly preferably at most 1.7% by weight P ₂ O ₅ . Disc-shaped glass article (1) according to one of the Claims 1 until 5 , wherein the glass and / or the glass article (1) _{comprises at least 0.8 wt .-% Na 2} O, wherein preferably the glass and / or the glass article (1) at most 8 wt .-% Na ₂ O, preferably at most 7 , 5 wt .-% Na ₂ O and particularly preferably at most 7 wt .-% Na ₂ O comprises. Disc-shaped glass article (1) according to one of the Claims 1 until 6th wherein the glass and / or the glass article (1) _{comprises at most 1% by weight K 2} O, preferably up to 0.8% by weight K ₂ O and particularly preferably up to 0.7% by weight K ₂ O and preferably at least 0.1% by weight of K ₂ O, particularly preferably at least 0.2% by weight of K ₂ O. Disc-shaped glass article (1) according to one of the Claims 1 until 7th , wherein the glass and / or the glass article (1) _{comprises at least 3 wt .-% Li 2} O, preferably at least 3.5 wt .-% Li ₂ O, and / or wherein the glass and / or the glass article (1) comprises at most 5.5 wt.% Li _{2 O.} Disc-shaped glass article (1) according to one of the Claims 1 until 8th wherein the glass and / or the glass article (1) _{comprises at most 69% by weight SiO 2} , preferably at most 67% by weight and / or wherein the glass and / or the glass article (1) comprises at least 57% by weight SiO ₂ comprises, preferably at least 59% by weight SiO ₂ and particularly preferably at least 61% by weight SiO ₂ . Glass article (1) according to one of the Claims 1 until 9 , wherein the glass and / or the glass article (1) _{comprises at most 25 wt .-% Al 2} O ₃ , preferably at most 21 wt .-% Al ₂ O ₃ and / or wherein the glass and / or the glass article (1) at least Comprises 17 wt% Al ₂ O ₃ . Glass article (1) according to one of the Claims 1 until 10 , the sum of the Al ₂ O ₃ and SiO ₂ content in the glass and / or glass article (1) being between at least 75% by weight and at most 92% by weight, preferably at most 90% by weight, and / or wherein the total content of network formers in the glass and / or glass article is not more than 92% by weight, particularly preferably not more than 90% by weight. Glass article (1) according to one of the Claims 1 until 11 , the thickness of the glass article (1) being at least 0.4 mm, preferably at least 0.5 mm. Glass article (1) according to one of the Claims 1 until 12th , the thickness of the glass article (1) being at most 3 mm, preferably at most 2 mm and particularly preferably at most 1 mm. Lithium-aluminum-borosilicate glass, comprising the following components in% by weight: SiO ₂ 57 to 69, preferably 59 to 69, particularly preferably 61 to 69, whereby the upper limit can preferably be 67 in each case, B ₂ O ₃ 0.5 to 7, preferably 0.5 to 5, particularly preferably 0.5 to 4.5, the lower limit preferably being 1.0% by weight of B ₂ O ₃ in each case, particularly preferably at least 1 in each case, 4% by weight B ₂ O ₃ , Al ₂ O ₃ 17 to 25, preferably 17 to 21, Li ₂ O 3 to 5.5, preferably 3.5 to 5.5, Na ₂ O 0.8 to 8, preferably 0.8 to 7.5, particularly preferably 0.8 to 7, where the sum of the Al ₂ O ₃ and SiO ₂ content, based on the information in% by weight, is preferably between at least 75 and at most 92, preferably at most 90.

Images