Classifications

• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C23/00—Other surface treatment of glass not in the form of fibres or filaments
  • C03C23/0005—Other surface treatment of glass not in the form of fibres or filaments by irradiation
  • C03C23/006—Other surface treatment of glass not in the form of fibres or filaments by irradiation by plasma or corona discharge
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
  • H01J9/24—Manufacture or joining of vessels, leading-in conductors or bases
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
  • H01J9/24—Manufacture or joining of vessels, leading-in conductors or bases
  • H01J9/245—Manufacture or joining of vessels, leading-in conductors or bases specially adapted for gas discharge tubes or lamps
  • H01J9/247—Manufacture or joining of vessels, leading-in conductors or bases specially adapted for gas discharge tubes or lamps specially adapted for gas-discharge lamps

Definitions

• the invention relates to a method for removing metal ions, especially Alkali ions from the surface layer of glass and ceramic bodies.
• Alkali ions especially Sodium and lithium, but also potassium ions cause a certain electrical conductivity or the like.
• Types of glass R.H. Doremus: "Glass Science”, Wiley, New York 1973, p. 146). Because of the high surface conductivity they can e.g. not be used as substrate glasses in microelectronics or for the construction of electrical circuit boards (D.J. Newman and M.J. Aggleton, Physics in Technology, Jan. 1977, pages 10-17).
• E-glass is used for this, which is almost alkali-free and consists, for example, of 50-55% Si0 2 , 8-12% B 2 0 3 , 13-15% A1 2 0 3 , 1-2% Na 2 0 + K 2 0, 15-17% CaO and 3-5% MgO (HH Dunken: "Physical Chemistry of the Glass Surface", VEB German Publisher for Basic Industry, L employzig 1981, p. 378). Alkali contents of 0.1% and less are now required. E-glass is relatively expensive due to its B p O content. When it melts, volatile fluorine compounds can escape. Measures to protect the environment from these substances are an additional cost factor. It is desirable to overcome these disadvantages by using inexpensive, conventional glasses, the surface layer of which has been freed from alkali ions. On the other hand, e-glasses with too high an alkali content could be optimized by removing residual alkali.
• Refractive index and reflectivity compared to pure Si0 are desirable low-cost flat glasses with reduced reflectivity and thus increased light transmission.
• the reflectivity of glasses can be reduced by applying layers whose refractive index lies between that of the glass (approx. 1.5) and that of the air (approx. 1.0).
• a thin layer of a suitable material is applied to the glass to be tempered.
• the anti-reflective layer can also through
• the remaining silicate framework has a lower refractive index. - ⁇ -
• the alkali-depleted glass of the top layer has a lower coefficient of expansion and exerts a compressive stress, which increases the work required for crack formation.
• the alkali ions are mostly removed by the action of acidic gases such as HC1 or S0 2 , S0 3 , S0C1 2 etc. together with water vapor on the glass surface which is several hundred degrees Celsius (HH Dunken, aa-.OrV S. 287; A. Sendt, Glastechn. Ber. 37 (2), 1964, 102-115; H. Scholze: "Glass. Nature, Structure and Properties", Springer, Berlin 1977, p. 222).
• the resistance of alkali-containing glasses can be increased if the alkali ions are removed from the surface layer. This is particularly interesting for preventing the corrosion of glass optical fibers and for preventing the undesired migration of alkali ions Glass vessels in the medical pharmaceutical field of application. Conventionally, the removal of the alkali ions from the surface can be done, for example, by treating the glass bodies heated to a few hundred degrees Celsius with SO 2 (RH Doremus, loc. Cit. P. 236; A. Sendt, loc. Cit. P. 110).
• the invention has for its object to provide a method with which by removing metal ions, especially alkali ions, both the electrical surface conductivity and the reflectivity of molded glass bodies can be reduced and their chemical resistance and mechanical strength can be improved.
• the shape of the glass body to be tempered should not be subject to any restrictions.
• the process should make it possible to treat the vitreous at room temperature so as not to change their volume properties and shape.
• the method should also be applicable in an analogous manner to enamelled bodies and bodies made of ceramic and other amorphous and crystalline materials.
• the object is, as explained in more detail in the claims, achieved in that metal surfaces, in particular alkali ions, are removed from the surface to be coated by treatment with a low-pressure plasma or a corona discharge.
• impurities for example sodium
• SiO p silicon oxide
• low-pressure plasmas can be used for the selective removal of metal ions, in particular alkali ions, from the surface layer of glass or under certain conditions, in particular when using non-oxidizing discharge gases, such as hydrogen, nitrogen or noble gases, which are not or little useful for surface cleaning use ceramic materials without the treated body having to be heated or an additional electrical potential applied.
• non-oxidizing discharge gases such as hydrogen, nitrogen or noble gases
• the effect is likely to be by bombarding the surface with gas ions and with high-energy, metastably excited gas particles, and possibly the "hard” UV radiation from the low-pressure plasma or the corona discharge.
• the outer layer becomes particularly poor in alkali ions and accumulates in SiO p , so that it becomes more "quartz-like" and corresponding glasses or ceramic bodies have the above advantageous properties.
• the treatment of bodies made of silicate glass in the low-pressure plasma is advantageously carried out in a reactor made of quartz glass or internally coated with SiO p , the low-pressure plasma being generated by an electrical high-frequency field of usually 13.56 MHz, which is applied via external electrodes or an external metal coil.
• the inner surfaces of the reactor which are exposed to the low-pressure plasma are advantageously coated with a material for the treatment of bodies made of glass or ceramic according to the invention which does not release any troublesome impurities under the conditions according to the process.
• the electrodes can also be arranged inside the reactor and the reactor can also consist of metal.
• suitable measures should be taken to prevent the transfer of metal particles to the bodies treated according to the invention (see: J.L. Vossen, Pure Appl. Chem. 5_2, pp. 1759-1765).
• the frequency of the field generating the plasma can be selected from a DC voltage to a high frequency.
• special microwave plasma reactors for example according to US Pat. No. 4,049,940
• the interiors of hollow bodies can be processed according to the invention.
• the construction of the reactor should ensure with advantageous application of the method that the bodies to be coated are located in the bright glowing zone of the discharge and are exposed to the bombardment of ionized and metastably excited gas particles and to UV radiation. All the surfaces of (arbitrarily shaped) bodies that are in contact with the low-pressure plasma are remunerated. Covered areas or those on which the bodies rest are not remunerated.
• the leakage rate of the gas supply system and the reactor should be less than 10 dm 3 Pa / sec when the method is advantageously used.
• the method according to the invention can also be carried out at pressures from 13.3 Pa (0.1 Torr) to 2 * 10 Pa (2 atm), advantageously 1 * 10 Pa (1 atm) using corona discharge devices.
• the frequency of the applied voltage can be selected from a DC voltage to a high frequency voltage, but is usually 10-40 kHz. Depending on the pressure and electrode spacing, the voltage is up to 20 kV.
• a corona discharge can alternatively be used at, for example, normal pressure, a voltage of 10 kV, a frequency of 10 kHz and a power of 1-10 kW.
• the decisive step in the method according to the invention that removes the metal ions consists of treating the body with a plasma, in an advantageous application of the invention in a low-pressure plasma (at, for example, 26.6 Pa) or with a plasma generated by corona discharge.
• a plasma in an advantageous application of the invention in a low-pressure plasma (at, for example, 26.6 Pa) or with a plasma generated by corona discharge.
• hydrogen, nitrogen or a are used as the discharge gas for this purpose
• Noble gas advantageously pure argon or helium used.
• the power transferred from the electric field to the low-pressure plasma can be between 0.01 and 1 watt per cm 3 plasma volume. In an advantageous application of the invention, it is in the range of 0.05 W / cm 3 .
• the parameters of pressure and power in the low-pressure plasma cannot be set completely independently of one another, since with a given reactor design and a given pressure, only a certain power can be transferred to the low-pressure plasma. The higher the pressure and power selected, the more it heats the surface of the treated body through the low-pressure plasma treatment.
• the duration of the plasma treatment is determined by the desired degree of depletion of metal ions. For alkali ions, this is typically in the range from a few minutes to an hour. This process step also kills microorganisms.
• Finished products made of easily and inexpensively to process alkali-containing glasses or ceramic materials or enamelled objects can be remunerated after their final shaping.
• the parts to be tempered do not have to be flat, they can have any shape.
• the method according to the invention can easily be controlled via the parameters pressure, power, duration and possibly temperature.
• the method can be used with suitable systems already available on the market, e.g. RIE ("Reactive Ion Etching") systems, corona discharge systems or microwave reactors.
• RIE Reactive Ion Etching
• the method according to the invention can be particularly advantageous in vacuum production lines, such as those e.g. be used in microelectronics, be integrated.
• FIG. 1 A corresponding arrangement is shown schematically in FIG. 1. It is particularly suitable for tempering small vitreous bodies.
• a glass reactor (1) with a volume of 0.9 dm 3 after removing a cap (2), is charged with the glass bodies to be tempered, closed again with the cap and evacuated with a suitable rotary pump or a diffusion pump. 3) read.
• the backflow of hydrocarbons from the pump is suppressed with a cold trap (4) or an absorption filter.
• Flat substrates (5) can be heated up to 250 ° C if necessary to intensify the treatment.
• an oil that is hot from an oil thermostat (6) is pumped through a substrate holder (7). If a cooling thermostat is used as an alternative, cooling is also possible.
• To clean the surface of the vitreous to be tempered from organic contaminants they are first exposed to an air plasma.
• Air is metered into the evacuated reactor with a fine regulating valve (8) until a constant pressure of 26.6 Pa (0.2 Torr) is reached and the low-pressure plasma is ignited by switching on a high-frequency generator (9).
• the reflected electrical power is minimized and the power consumed by the low-pressure plasma is set to 40 W by means of an adaptation network (10).
• the power consumed is calculated as the difference between the fed-in and reflected power with a wattmeter (11) certainly.
• the generator is switched off, the metered-in air is switched off and the reactor is pumped empty to the lowest achievable pressure.
• a 30-minute plasma treatment with argon (3-ring) at 26.6 Pa (0.2 Torr) and 40 W is now carried out in the manner described.
• the reactor is aerated via an aeration valve (12) and the tempered glass body is removed from the reactor.
• FIGS. 2 to 7 show ESCA ("Electron Spectroscopy for Chemical Analysis") spectra of two cover glasses for microscopy purposes, one of which remained untreated, the other was subjected to the method according to the invention described in the exemplary embodiment.
• the overview spectra (FIGS. 2 and 3) show the signals of all elements present in the glass surface. the absence of signals of sodium and potassium in FIG. 3 can be clearly seen.
• FIGS. 4 to 7 show the signals of potassium, sodium and aluminum in higher resolution.
• FIG. 4 shows the 2p 3 and the 2p 1 signals of potassium (the signals at 285 and 288.5 eV come from carbon impurities) at the untreated glass surface at binding energies (BE) of 293.5 eV and 296.0 eV .
• BE binding energies
• FIG. 5 shows the 2s signal of sodium (63.4 eV) and the 2p signal of aluminum (74.3 eV) on the untreated glass surface.
• FIG. 7 shows the corresponding area of the spectrum of the treated surface. The signals from sodium and aluminum have disappeared.
• the ESCA spectra demonstrate that potassium, sodium and aluminum are removed from the surface layer of the glass by the process according to the invention.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Health & Medical Sciences (AREA)
• Toxicology (AREA)
• Life Sciences & Earth Sciences (AREA)
• Plasma & Fusion (AREA)
• Physics & Mathematics (AREA)
• General Chemical & Material Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Surface Treatment Of Glass (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Glass Compositions (AREA)

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• 1985
  • 1985-05-21 DE DE19853518197 patent/DE3518197A1/de active Granted
• 1986
  • 1986-05-16 WO PCT/DE1986/000209 patent/WO1986007051A1/de unknown
  • 1986-05-16 JP JP61502763A patent/JP2523561B2/ja not_active Expired - Lifetime
  • 1986-05-16 EP EP86903215A patent/EP0221968A1/de not_active Withdrawn
• 1989
  • 1989-07-24 US US07/384,033 patent/US4983255A/en not_active Expired - Fee Related

Non-Patent Citations (1)

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