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 [Search a list of Patent Appplications for class 501]   CLASS 501,COMPOSITIONS: CERAMIC
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SECTION I - CLASS DEFINITION

This is the generic class for:

Glass compositions and compositions for making glass, i.e., glass batch compositions, devitrified glass-ceramic compositions and processes for producing such compositions. These compositions may be regarded as thermoplastic compositions.

Refractory compositions comprising primarily earthy, inorganic materials, and/or elemental carbon.

Fired clay containing compositions in the nature of porcelain, earthenware, and similar materials. These compositions may be regarded as thermosetting compositions.

See the Glossary for the definition of the term "ceramic".

SECTION II - LINES WITH OTHER CLASSES AND WITHIN THIS CLASS

Optional ingredients. Disclosures reciting an optional ingredient, such as a statement that a composition includes a range of concentration of the ingredient, including zero percent as the lower end of the range (i.e., containing or comprising 0 - X percent by weight of that ingredient) are classified in a more generic subclass and cross-referenced to an indented subclass which provides for the presence of that ingredient. As an example, a refractory composition which comprises 0 - 10 percent of silicon carbide might be classified as an original in subclass 87 and cross-referenced in subclass 88.

Mol percent and weight percent. When in a disclosure otherwise classifiable in subclasses 54, 55, 73, 121, or 131 recites the concentration of the material specified in the subclass title is in mol percent rather than weight percent, it may be necessary to calculate the equivalent weight percent to classify the disclosure properly.

1. A COMPOUND, PER SE, IS CLASSIFIED IN A COMPOUND CLASS REGARDLESS OF UTILITY.

See References to Other Classes, below, for compound classes.

2. COMPOSITION OR MATERIAL.

A. The rules for determining Class placement of the Original Reference (OR) for claimed chemical compositions are set forth in the Class Definition of Class 252 in the SECTION LINES WITH OTHER CLASSES AND WITHIN THIS CLASS, subsection COMPOSITION CLASS SUPERIORITY, which includes a hierarchical ORDER OF SUPERIORITY FOR COMPOSITION CLASSES.

It is the general rule of classification to classify a process of preparing a composition along with the composition. In those circumstances where only a process of preparing a composition is claimed and there is no claim to a composition, the claim would be classified identically as if it were a composition claim.

B. Lines With Article Or Product Classes.

1. As a general rule, a product (article) is classified with the class specifically providing for the same or a generic class which can take the same.

2. This class (501) provides for an article or product defined in terms of its compositions.

3. An article or product defined by B, 2 above, combined with significant structure for another class will be classified in the class providing for the structure and crossed to Class 501.

4. Subject matter involving multiple claimed inventions--i.e., claims for both Class 501 and those classes in References to Other Classes below that are related to "Composition or Material," section A or section B--will be classified in said class and crossed to Class 501.

See References to Other Classes for article or product classes.

C. PROCESS AND APPARATUS CLASSES

See References to Other Classes, below for process and apparatus classes.

D. SPECIAL CLASSES

See References to Other Classes, below for special classes.

SECTION III - REFERENCES TO OTHER CLASSES

SEE OR SEARCH CLASS:

13Electric Furnaces,   subclass 35 for furnace linings. (see Lines With Other Classes, "Composition or Material," section B, above)
23Chemistry: Physical Processes,   subclass 230 for physical processes pertaining to ceramic material. (Process class)
29Metal Working,   appropriate subclasses for a process of making articles having ceramic material. (Process class)
30Cutlery,   subclass 345 for structured cutlery articles defined in part in terms of the materials of its makeup. (see Lines With Other Classes, "Composition or Material," section B, above)
34Drying and Gas or Vapor Contact With Solids,   for process and apparatus for drying ceramic material. (Process and apparatus class)
52Static Structures (e.g., Buildings),   appropriate subclasses for structures of that class made of ceramic material. (see Lines With Other Classes, "Composition or Material," section B, above)
55Gas Separation,   appropriate subclasses for apparatus having ceramic filtering material, especially subclasses 522+ ; particularly subclass 523 for specific media material, ceramic or sintered. (see Lines With Other Classes, "Composition or Material," section B, above)
65Glass Manufacturing,   appropriate subclasses for glass working or treating. See the class definition of Class 65 for the line between Classes 65 and 501, especially the Glossary therein for the definitions of glass working and glass treating, subclasses 2+ for such process of making fibers or filaments; subclasses 19+ for processes employing slag; subclasses 21+ for bead making; subclass 22 for preforming; subclass 33 for devitrifying or vitrifying crystalline glass; subclasses 36+ for fusion bonding of glass to a preformed part, subclasses 60.1+ for a process involving glass working or treating, as well as coating; and subclasses 134+ for processes of purifying or homogenizing molten glass. (Process class)
71Chemistry: Fertilizers,   appropriate subclasses for fertilizers containing ceramic material. (see Lines With Other Classes, "Composition or Material," section B, above)
71Chemistry: Fertilizers,   appropriate subclasses for process of using ceramic materials in fertilizers. (Process class)
75Specialized Metallurgical Processes, Compositions for Use Therein, Consolidated Metal Powder Compositions, and Loose Metal Particulate Mixtures,   subclasses 228+ for consolidated metal powders which may contain a ceramic material in which the metal particles form a continuous phase, but the ceramic particles do not form a continuous phase. (Special Class)
75Specialized Metallurgical Processes, Compositions for Use Therein, Consolidated Metal Powder Compositions, and Loose Metal Particulate Mixtures,   subclasses 201+ for pyrometallurgy process involving sintering a metal and nonmetal. (Process class)
106Compositions: Coating or Plastic,   appropriate subclasses for nonceramic coating or plastic compositions, especially subclasses 74+ for alkali metal silicate containing compositions; subclasses 85+ for inorganic settable compositions; particularly subclasses 100+ for Portland cement making; subclasses 109+ for making cementitious materials from gypsum; subclass 312 for opacifiers intended for inclusion in enamel compositions; and subclass 313 for fluxes intended to be used in ceramic compositions. (Process/apparatus class)
110Furnaces,   subclass 323 for refractory type baffle or heat retainer structure of a furnace and subclasses 338+ for brick element. (apparatus class)
117Single-Crystal, Oriented-Crystal, and Epitaxy Growth Processes; Non-Coating Apparatus Therefor,   for processes and non-coating apparatus for growing therein-defined single-crystal of all types of materials, including ceramic. (Process/apparatus class)
126Stoves and Furnaces,   appropriate subclasses for stoves and furnaces which may contain a ceramic element, especially subclass 400 for fireless cookers which are heat accumulators; subclasses 204+ for body warmers; and subclass 273.5 for ovens. (apparatus class)
200Electricity: Circuit Makers and Breakers,   subclasses 262+ for electrical contacts composed of named material. (see Lines With Other Classes, "Composition or Material," section B, above)
201Distillation: Processes, Thermolytic,   subclass 18 for process of using apparatus of the class of particular composition. (Process/apparatus class)
204Chemistry: Electrical and Wave Energy,   subclasses 280+ for electrolytic electrodes. (see Lines With Other Classes, "Composition or Material," section B, above)
204Chemistry: Electrical and Wave Energy,   appropriate subclasses, especially subclasses 157.15+ for processes of preparing a specific compound utilizing a wave energy process. (Compound class)
210Liquid Purification or Separation,   appropriate subclasses for process and apparatus using ceramic material in a liquid separation operation. (Process/apparatus class)
216Etching a Substrate: Processes,   for methods of chemically etching ceramic materials. (Process class)
219Electric Heating,   subclasses 73+ for a slag composition being used as an environment for electric heating. (Process/apparatus class)
241Solid Material Comminution or Disintegration,   appropriate subclasses for process or apparatus for comminuting materials. See section 2 of the Class 241 definition for the class line. (Process/apparatus class)
249Static Molds,   subclass 134 for molds having named material classifiable, per se, in this class (501). (see Lines With Other Classes, "Composition or Material," section B, above)
252Compositions,   subclass 62 for sound or heat insulators defined by their composition which is other than ceramic. (see Lines With Other Classes, "Composition or Material," section B, above)
257Active Solid-State Devices (e.g., Transistors, Solid-State Diodes),   appropriate subclasses for those devices which contain ceramic material, including subclass 700 , 701+, especially 703 and 705 for ceramic housing or package materials. (see Lines With Other Classes, "Composition or Material," section B, above)
261Gas and Liquid Contact Apparatus,   subclasses 94+ and 100+ for porous contact devices in the form of a mass or sheet. (see Lines With Other Classes, "Composition or Material," section B, above)
264Plastic and Nonmetallic Article Shaping or Treating: Processes,   for processes of molding or shaping compositions of matter which include significant molding or shaping operation. The line between this class (501) and Class 264 is as follows: Class 501 takes processes of making compositions within the class definition even though including the step of molding, when such step is claimed broadly. Broad references to extruding, spinning into a setting medium (without naming the medium) or sheeting in a claim to the preparation of a composition of matter, are considered broad molding steps. Also the statement that heat and pressure are used during the molding, whether or not specific temperatures or specific pressures are recited, is not considered sufficient of itself to take a patent claiming a process of preparing a composition out of this class (501). See especially subclasses 239+ for shaping or molding a ceramic article; and digest 39 for processes of treating clay before and after molding. For a detailed discussion of the line between Class 264 and the composition classes, see the definitions of Class 264 and the notes to subclasses 603+ therein. (Process/apparatus class)
266Metallurgical Apparatus,   subclass 280 for linings for metallurgical apparatus. (apparatus class)
338Electrical Resistors,   appropriate subclasses for electrical resistors having ceramic material. (see Lines With Other Classes, "Composition or Material," section B, above)
359Optical: Systems and Elements,   appropriate subclasses for articles of that class having ceramic materials, especially glass, which may be classified, per se, in this class (501). (see Lines With Other Classes, "Composition or Material, section B, above)
361Electricity: Electrical Systems and Devices,   subclass 320 and 321.1+ for fixed capacitors having ceramic and glass materials. (see Lines With Other Classes, "Composition or Material," section B, above)
376Induced Nuclear Reactions: Processes, Systems, and Elements,   subclasses 409+ for nuclear fuels with significant structural features which may be made of a named ceramic composition. However, ceramic compositions, per se, which may be useful to construct nuclear fuel elements are classified in this class (501). (see Lines With Other Classes, "Composition or Material," section B, above)
404Road Structure, Process, or Apparatus,   subclasses 17+ for preparation of pavements; and subclasses 72+ for processes of preparing road structures which may involve a Class 501 composition. (see Lines With Other Classes, "Composition or Material," section B, above)
404Road Structure, Process, or Apparatus,   subclasses 75+ for processes of treating earth or a roadway in situ including the application of a ceramic material thereto, and see the note to Class 501 in the main class definition of Class 404. (Process/apparatus class)
405Hydraulic and Earth Engineering,   subclasses 263+ for processes and apparatus for chemical treatment of earth formations in situ to condition the formation or to prevent undesired movement thereof. (Process/apparatus class)
422Chemical Apparatus and Process Disinfecting, Deodorizing, Preserving, or Sterilizing,   subclasses 245.1+ for non-coating crystallization apparatus not including means for chemical reaction not provided for elsewhere and subclasses 129+ for non-coating crystallization apparatus including means for chemical reaction and not provided for elsewhere.(Process/apparatus class)
423Chemistry of Inorganic Compounds,   appropriate subclasses for inorganic compound or nonmetallic element disclosed or claimed having a utility in a Class 501 composition. (Compound class)
425Plastic Article or Earthenware Shaping or Treating: Apparatus,   appropriate subclasses for apparatus for shaping or treating ceramic compositions other than glass. (apparatus class)
427Coating Processes,   appropriate subclasses for processes of coating with ceramic compositions. (Process class)
428Stock Material or Miscellaneous Articles,   subclasses 304.4+ for stock material containing one cellular or porous component which may comprise a ceramic composition; subclass 426 for nonstructural laminated stock material which includes a glass composition; subclasses 446+ for nonstructural laminated stock material which includes a composition including silicon or a compound of silicon; and 539.5, for stock material containing free metal particles and ceramic particles wherein there is a metal continuous phase interengaged with a nonmetal continuous phase as a result, e.g., of a sintering operation. (See Lines With Other Classes, "Composition or Material," section B, above)
428Stock Material or Miscellaneous Articles,   subclass 38 for glass containing wire mesh reinforcement; subclasses 426+ for plural layer stock material in which at least one layer contains a glass; and subclass 539.5 for sintered compacts comprising both metal or alloy particles and ceramic particles in which there is present a metal continuous phase interengaged with a ceramic continuous phase. (Special Class)
429Chemistry: Electric Current Producing Apparatus, Product, and Process,   subclasses 247+ for battery separators which may comprise a ceramic material. (Process/apparatus class)
429Chemistry: Electrical Current Producing Apparatus, Product, and Process,   appropriate subclasses for chemical current producing structures which may comprise a ceramic component and for processes of producing electric current by chemical means utilizing or producing a ceramic composition. (See Lines With Other Classes, "Composition or Material," section B, above)
432Heating,   subclasses 1+ for a residual process of heating or calcining an object or material which is clearly distinct from the composition and for processes and apparatus for the firing of ceramic materials not involving the shaping thereof. (Process/apparatus class)
433Dentistry,   appropriate subclasses for ceramic dental articles. (see Lines With Other Classes, "Composition or Material," section B, above)
442Fabric (Woven, Knitted, or Nonwoven Textile or Cloth, etc.),   appropriate subclasses for glass fiber fabric. (Special Class)
451Abrading,   subclasses 28+ for an abrading process using ceramic materials. (Process class)
505Superconductor Technology: Apparatus, Material, Process,   subclasses 100+ for high temperature (Tc 30 K) superconducting materials, per se, or subclasses 300+ for processes of producing same. (See Lines With Other Classes, "Composition or Material," section B, above)
520Synthetic Resins or Natural Rubbers,   the series for synthetic resin, per se, even though such resin is disclosed or claimed as having a Class 501 utility. A resin, per se, is one containing no intentional additive to perfect it for a Class 501 purpose. See the remainder of the class (260) for an organic compound having a Class 501 utility not provided for elsewhere. This portion of Class 260 is being reclassified into the 530 to 570 series of classes. See the search notes thereunder. (Compound class)
526Synthetic Resins or Natural Rubbers,   for polymers of unsaturated monomers only, per se, even if disclosed or claimed as having a Class 501 utility. (Compound class)
588Hazardous or Toxic Waste Destruction or Containment,   subclasses 249 through 260for the permanent containment and storage of hazardous or toxic waste, particularly subclasses 252-253 which may involve vitrification. (Process class)

SECTION IV - GLOSSARY

The meaning to be given to the various "art" terms appearing in this class, but which have not been included in the Glossary below, is the same as that generally accepted or in common usage. However, certain terms employed in this class, which are included below, have been assigned definitions tailored to meet the needs of this class and therefore those may be more restricted or less limited or even altogether different from those in common usage.

ALKALINE EARTH METAL

Alkaline Earth Metal is considered to be generic to calcium, strontium, and barium. In this class (501), magnesium is not considered to be an alkaline earth metal and compositions containing magnesium compounds are generally provided for apart from those of alkaline earth metals.

CERAMIC

Inorganic compositions which are heat treated to harden them during their manufacture or subsequent use by firing, calcining, sintering, or fusion of at least a portion of the inorganic material, including glass compositions, fired clay compositions which form, e.g., porcelain or brick, and refractories. Such materials typically, but not necessarily, include earthy materials, such as metal (and especially mixed metal) silicates.

CLAY

The naturally occurring earthy materials (or artificial compositions having generally equivalent chemical and physical properties) containing a substantial proportion (30 percent or more) of colloidal particles (under .002mm.), and which becomes plastic when mixed with water and which plastic material is capable of being hardened when fired and containing a major proportion of hydrated aluminum silicates which are derived by the weathering or decomposition of granite or other feldspathic rock.

(1) Note. Many natural materials are considered to be clays, e.g., kaolin, fire clays, ball clays, china clays, bentonite, fuller"s earth, bauxite, montmorillonite, halloysite, and argillaceous earths.
(2) Note. Typical clay containing ceramic compositions or articles are, e.g., common or face brick, structural blocks, porcelain bricks, pottery, china, terra cotta, tile, sewer pipe, and some coating and filling compositions.

EARTHENWARE, PORCELAIN

These terms designate fine grained or fully vitreous, high fired white or translucent ceramic materials, frequently, but not always containing clay or similar plastic components. Among many terms used to designate somewhat similar materials are stoneware, earthenware, porcelain, pottery, china, whiteware, tile, crockery, sanitaryware, terra cotta, bisque, rakuware, and slip cast ware. They are not intended for use in the high temperature or corrosive environments where materials referred to as refractories are typically employed.

FIBER

A slender, elongated structure of relatively small, uniform diameter having a much greater length, which may have a relatively short finite length or an indeterminate length.

FRIT

A glass composition in a powdered or granulated state prepared by fusing the glass and quenching it in a cold liquid. Frits form an important part of the batches used in compounding glazes and enamels.

GLASS

Inorganic compositions which solidify from the molten state without crystallizing, to have that molecular disorder characteristic of the glass state, which have no definite melting point, are incapable in the solid state of permanent deformation, which fracture when subjected to deformation tension and include as components at least one "glass former" material.

(1) Note. Typical glass formers are, e.g., oxides of silicon, beryllium, boron, germanium, phosphorus, vanadium, lead, tin, zinc, zirconium, and titanium, as well as such nonoxide compounds as GeS, metal fluorides, or iodides, and some metallic selenides, tellurides, arsenides, and phosphides. These compositions may also include other oxides devoid of glass forming tendencies, e.g., oxides of alkali metals, alkaline earth metals, and magnesium.
(2) Note. Many ceramic compositions containing primarily slag, the by product of metal refining and smelting are considered to be glasses.
(3) Note. Neither transparency to light nor the absence of color are necessary for a composition to be considered as a glass for the purpose of this class.
(4) Note. Water glass, clear synthetic resin compounds, and isinglass are not considered to be glass for the purpose of classification in Class 501.
(5) Note. Organic, noncrystalline solid materials, such as synthetic resins which may be referred to as organic glasses, are not considered to be glass for the purpose of classification in Class 501.

PORE FORMING (POROUS, MULTICELLULAR)

These terms embrace porous compositions, compositions intended to be further treated to make them porous or processes for effecting the porosity or multicellularity. A positive step for causing porosity must be recited and porosity which is the result of including a naturally porous material in the composition is not classified in the pore-forming subclasses of this class (501).

RARE EARTH ELEMENT

As used in this class (501), this term encompasses those elements having atomic numbers from 57 through 71 inclusive, and 89+. Thus, the following elements are herein treated as rare earth elements: lanthanum, cerium, praesodymium, neodymium, promethium, samarium, europium, gadolmium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutecium, actinium, thorium, protoactinium, uranium, neptunium, and plutonium.

REFRACTORY

Compositions which are specifically formulated to be resistant to abrasion, corrosion and physical or chemical disintegration when subjected to high temperatures, chemically corrosive environments and/or rapid temperature changes.

(1) Note. Refractory materials are typically used to produce furnace and kiln linings, fire brick, kiln furniture and saggers, and pyroceramic cones.
(2) Note. Among naturally occurring materials widely used in making refractory products are, e.g., magnesite, dolomite, and chrome- magnesite.

VITREOUS, VITRIFY

Vitrification is the progressive fusion of the particles in a ceramic body. As vitrification progresses, the proportion of glassy bond increases and the apparent porosity of the substance decreases. Glass in a massive form (rather than in a frit or powder) and porcelain are considered to be fully vitrified.

SUBCLASSES

[List of Patents for class 501 subclass 1]    1CERAMIC COMPOSITIONS:
 This subclass is indented under the class definition.  Compositions other than Portland cement or cementitious material prepared from gypsum, having an inorganic base, which are heat treated to effect hardening or fusion followed by hardening when cooled either during their manufacture or during subsequent use by firing, calcining, sintering, or fusion of at least part of the inorganic material, and processes not elsewhere classified for their production.
(1) Note. Included herein are glass compositions, refractory materials employed in furnace and crucible walls, kiln-fired clay products, and similar materials.
(2) Note. Ceramic dielectrics, such as those containing barium titanate, are classified in this or indented subclasses unless they are disclosed or claimed as being piezoelectric, in which case, they are classified in Class 252, Compositions, subclass 62.9, or in Class 310, Electric Generator or Motor Structure, subclasses 8+ if claimed as having a particular shape which is particular to the piezoelectric property. If the ceramic dielectric is claimed or disclosed broadly as having piezoelectric properties, the ceramic dielectric is not classified here either as an original or a cross reference, but is classified in appropriate class provided for the piezoelectric composition, e.g., Class 252 or Class 310 as noted above.

SEE OR SEARCH CLASS:

52Static Structures (e.g., Buildings),   appropriate subclasses for cast monoliths or ceramic members characterized by significant structural configuration.
75Specialized Metallurgical Processes, Compositions for Use Therein, Consolidated Metal Powder Compositions, and Loose Metal Particulate Mixtures,   subclasses 228+ for consolidated compositions of metals or alloys including those containing ceramic or refractory or other nonmetallic components, e.g. cermets.
106Compositions: Coating or Plastic,   subclasses 739+ for the making of Portland cement; subclasses 772+ for the preparation of cementitious materials from gypsum; and subclass 313 for fluxes which are to be used in the production of ceramic compositions.
252Compositions,   subclasses 301.4+ for inorganic luminescent compositions.
264Plastic and Nonmetallic Article Shaping or Treating: Processes,   appropriate subclass for processes, within the class definition, including a significant molding operation or a significant treatment of a molded article. In particular, see subclass 30 , 31+, 43+, 125, and 603+ therein. For a detailed discussion of the line between Class 264 and the composition classes, see the definitions of Class 264 and the notes to subclasses 56+ therein.
  
[List of Patents for class 501 subclass 2]    2Devitrified glass ceramics:
 This subclass is indented under subclass 1.  Compositions containing a crystalline phase embedded in a glassy (amorphous) phase, which crystalline phase is produced by cooling a molten glass composition to a temperature which causes a portion only of the composition to crystallize while the remainder of the composition (the matrix) solidifies in the amorphous or glassy state.
(1) Note. The crystalline phase is typically uniformly dispersed throughout the glassy phase and it must constitute at least 50 percent by weight of the total composition.
(2) Note. The subclasses indented hereunder are established on the basis of the nature of the crystalline phase. Patents placed as originals in the indented subclasses may be cross-referenced when appropriate in other subclasses of this class on the basis of the nature of the glassy matrix phase.
(3) Note. Documents classified as originals in this and indented subclasses are cross-referenced on the basis of the chemical nature of the glass composition disclosed into subclasses 40, 41+, and/or 53+, as appropriate.
(4) Note. Documents classified as originals in this and indented subclass which are directed to optical glass compositions are cross-referenced to subclasses 900+.
  
[List of Patents for class 501 subclass 3]    3Halogen containing crystalline phase (e.g., fluormica, etc.):
 This subclass is indented under subclass 2.  Compositions in which the crystalline phase includes a halogen atom.
(1) Note. The crystalline phase may comprise, e.g., fluormica, etc.
  
[List of Patents for class 501 subclass 4]    4Silica containing crystalline phase (e.g., stuffed quartz, cristobalite, etc.):
 This subclass is indented under subclass 2.  Subject matter wherein the crystalline phase comprises silica.
(1) Note. The crystalline phase may comprise, e.g., the so-called stuffed quartz, cristobalite (a crystalline form of SiO2), etc.
  
[List of Patents for class 501 subclass 5]    5Binary, ternary, quaternary, etc., metal silicate crystalline phase (e.g., mullite, diopside, sphene, plagioclase, slagcerams free of alumina, etc.):
 This subclass is indented under subclass 2.  Subject matter wherein the crystalline phase comprises silicates of two or more metals.
(1) Note. The crystalline phase may comprise, e.g., diopside (CaMgSiO6), sphene (CaTiSiO5), plagioclase (atriclinic feldspar), a slagceram free of Al2O3, etc.
  
[List of Patents for class 501 subclass 6]    6Alkali metal aluminosilicate crystalline phase:
 This subclass is indented under subclass 5.  Compositions in which the silicate comprises an alkali metal aluminosilicate.
  
[List of Patents for class 501 subclass 7]    7Lithium aluminosilicate (e.g., spodumene, eucryptite, petalite, etc.):
 This subclass is indented under subclass 6.  Compositions in which the alkali metal aluminosilicate comprises a lithium aluminosilicate.
(1) Note. The aluminosilicate may be, e.g., spodumene (Li,Na)2Al2Si4O12), eucryptite (LiAlSiO4), petalite (Li2O.Al2O3.8SiO2), etc.
  
[List of Patents for class 501 subclass 8]    8Divalent metal oxide aluminosilicate crystalline phase (e.g., anorthite, slagcerams, etc.):
 This subclass is indented under subclass 5.  Compositions in which the silicate comprises a divalent metal oxide aluminosilicate.
(1) Note. The silicate may be an aluminosilicate of an alkaline earth metal, magnesium, zinc, or zirconium, e.g., anorthite (CaAl2Si2O3), a slagceram, etc.
  
[List of Patents for class 501 subclass 9]    9Magnesium aluminosilicate (e.g., cordierite, etc.):
 This subclass is indented under subclass 8.  Compositions in which the silicate comprises a magnesium aluminosilicate.
(1) Note. The silicate may be, e.g., cordierite (Mg4Al8O6(SiO3)10, etc.
  
[List of Patents for class 501 subclass 10]    10Nonsilica and nonsilicate crystalline phase (e.g., spinel, barium titanate, etc.):
 This subclass is indented under subclass 2.  Compositions in which the crystalline phase does not include silica or a silicate.
(1) Note. The crystalline phase may comprise, e.g., spinel (MgAl2O4), gaehnite (ZnAl2O4), franklinite (Fe, Zn, Mn) Fe2O4) chromite (FeCr2O4), barium titanate (BaTiO3), etc.
  
[List of Patents for class 501 subclass 11]    11Glass compositions, compositions containing glass other than those wherein glass is a bonding agent, or glass batch forming compositions:
 This subclass is indented under subclass 1.  Compositions which comprise a glass or compositions intended to be heat treated so as to form a glass.
(1) Note. To be classified herein, the chemical nature of the glass composition must be unspecified.
(2) Note. A typical disclosure appropriate for this subclass might be, e.g., a product by process claim, etc.
(3) Note. Compositions containing both glass and nonglass materials in which the glass serves merely as a binder for particles of the other material are not included herein, but are classified on some other basis.
(4) Note. This and indented subclasses include compositions of enamels and glazes, etc., which are glasses.
(5) Note. Documents classified as originals in this and indented subclasses which disclose optical glass compositions are cross-referenced in subclasses 900+.

SEE OR SEARCH CLASS:

65Glass Manufacturing,   subclasses 134+ for processes of purifying or homogenizing molten glass.
220Receptacles,   subclasses 2.1+ for envelopes for electric lamps, electronic tubes and similar devices which are made of glass. Where no more is claimed than an envelope of a specific composition of glass the patent is classified in this class (501). Where the composition is claimed and also some structure of the envelope, the patent is classified in Class 220.
  
[List of Patents for class 501 subclass 12]    12Made by gel route:
 This subclass is indented under subclass 11.  Compositions which have been prepared by a method other than melting including at least one step in which the glass forming ingredients are in a gel or sol state, and glass making processes involving such a step.
(1) Note. Documents classified as originals in this subclass are cross-referenced on the basis of the chemical nature of the glass composition disclosed into subclasses 40, 41+, and/or 53+, as appropriate.
(2) Note. Documents classified as originals in this subclass which disclose optical glass compositions are cross-referenced in subclasses 900+.

SEE OR SEARCH CLASS:

65Glass Manufacturing,   subclasses 134+ for processes of homogenizing or purifying molten glass.
516Colloid Systems and Wetting Agents; Subcombinations Thereof; Processes of Making, Stabilizing, Breaking, or Inhibiting,   subclasses 98+ for colloid systems of continuous or semicontinuous solid phase with discontinuous liquid phase (gels, pastes, flocs, coagulates) or agents for such systems or making or stabilizing such systems or agents, when generically claimed or when there is no hierarchically superior provision in the USPC for the specifically claimed art.
  
[List of Patents for class 501 subclass 13]    13Radiation color change responsive:
 This subclass is indented under subclass 11.  Compositions which are capable of reversibly changing color or darkening in response to the presence of electromagnetic radiation and which if darkened thereby fade when the electromagnetic radiation is removed.
(1) Note. Documents classified as originals in this subclass are cross-referenced on the basis of the chemical nature of the glass composition disclosed into subclasses 40, 41+, and/or 53+, as appropriate.
(2) Note. Documents classified as originals in this subclass which disclose optical glass compositions are cross-referenced in subclasses 900+.

SEE OR SEARCH CLASS:

252Compositions,   subclass 300 for optical filter compositions and subclass 600 for other radiation sensitive compositions.
430Radiation Imagery Chemistry: Process, Composition, or Product Thereof,   subclass 13 for imaged products containing an image within a transparent base.
  
[List of Patents for class 501 subclass 14]    14Enamels, glazes, or fusion seals (e.g., raw, fritted, or calcined ingredients):
 This subclass is indented under subclass 11.  Compositions disclosed as vitreous enamels, or glazes, or similar compositions which are intended for use as seals between glass and/or metal components of various devices.
(1) Note. The compositions in this and indented subclasses have typically been cross-referenced below on the basis of their specific ingredient content, e.g., to subclasses 21+ for frit compositions, subclass 40 for nonoxide glasses, subclasses 41+ for nonsilica and nonsilicate containing oxide glasses, and subclasses 53+ for Si02 containing glasses.
(2) Note. Documents classified as originals in this and indented subclasses which disclose optical glass compositions are cross-referenced in subclasses 900+.

SEE OR SEARCH CLASS:

106Compositions: Coating or Plastic,   subclass 312 for opacifiers for enamels, per se.
427Coating Processes,   for processes of enameling with vitreous enamel compositions.
523Synthetic Resins or Natural Rubbers,   appropriate subclasses, particularly subclass 170 for a composition containing a synthetic resin or Natural Rubbers and having utility as an enamel composition for glass or for a medium or binder in the preparation of glass enamel or to processes of preparing said composition.
  
[List of Patents for class 501 subclass 15]    15Fusion seals (frit plus material other than glass):
 This subclass is indented under subclass 14.  Compositions disclosed for use as seals between other ceramic glass, and/or metal components of various devices, and containing a frit plus some other ingredient which is not a glass.
(1) Note. These compositions are sometimes disclosed as glass solders.

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17+,for glass compositions containing a frit plus a material other than glass which are not disclosed as seal glasses.
  
[List of Patents for class 501 subclass 16]    16Plural diverse frits:
 This subclass is indented under subclass 14.  Compositions comprising two or more distinct frits having different compositions.
  
[List of Patents for class 501 subclass 17]    17Frit plus material other than glass (e.g., color, opacifier, mill additions, etc.):
 This subclass is indented under subclass 14.  Compositions which comprise a frit pulse at least one other material which is not a glass.
(1) Note. The other material may be, e.g., an opacifying agent, a coloring agent, or any material added during the milling or other comminuting operation to enhance that process or to improve the properties of the product of that process.
  
[List of Patents for class 501 subclass 18]    18Titanium zirconium compound as other material:
 This subclass is indented under subclass 17.  Compositions which contain a compound of titanium or zirconium as the other material.
  
[List of Patents for class 501 subclass 19]    19Free metal as other material:
 This subclass is indented under subclass 17.  Subject matter in which the other material is a free metal.
(1) Note. The free metal may be, e.g., in the form of copper flakes, aluminum powder, etc.
(2) Note. See the class definition of this class (501) for the general lines between this class and other composition classes relative to cermets, powder metallurgy compacts and similar materials.
  
[List of Patents for class 501 subclass 20]    20With vehicle or suspending agent (i.e., slip):
 This subclass is indented under subclass 17.  Compositions which contain a liquid vehicle or a suspending agent.
(1) Note. Such a composition containing a liquid vehicle is frequently referred to as a slip.
  
[List of Patents for class 501 subclass 21]    21Chemically specified frit compositions:
 This subclass is indented under subclass 14.  Compositions which are in a powdered or comminuted form, defined in terms of their chemical content.
  
[List of Patents for class 501 subclass 22]    22Lead containing:
 This subclass is indented under subclass 21.  Compositions which include lead or a lead compound.
  
[List of Patents for class 501 subclass 23]    23And titanium or zirconium:
 This subclass is indented under subclass 22.  Compositions which additionally include titanium or zirconium or a compound of either of them.
  
[List of Patents for class 501 subclass 24]    24Phosphorus containing:
 This subclass is indented under subclass 21.  Compositions which contain phosphorus or a compound of phosphorus.
  
[List of Patents for class 501 subclass 25]    25Halogen containing:
 This subclass is indented under subclass 21.  Compositions which include a halogen atom, either as a free element or in the form of a halogen compound.
  
[List of Patents for class 501 subclass 26]    26Zinc containing:
 This subclass is indented under subclass 21.  Compositions which include zinc or a zinc compound.
  
[List of Patents for class 501 subclass 27]    27Glass batch forming compositions (i.e., glass batch compositions):
 This subclass is indented under subclass 11.  Compositions which are intended to be heated sufficiently for its ingredients to fuse into a glass.
(1) Note. The ingredients of the batch may include a previously prepared glass, such as scrap glass or cullet.
(2) Note. These compositions are sometimes referred to as glass furnace charges.
  
[List of Patents for class 501 subclass 28]    28Slag containing:
 This subclass is indented under subclass 27.  Compositions which comprise slag, the nonmetallic by product from various metallurgical processes.
  
[List of Patents for class 501 subclass 29]    29Pellet or agglomerate containing:
 This subclass is indented under subclass 27.  Compositions which include at least one ingredient in the form of shaped particles, e.g., pellets, granules, briquettes, nodules, etc.
  
[List of Patents for class 501 subclass 30]    30Halogen containing:
 This subclass is indented under subclass 27.  Compositions which include a free halogen or a halogen compound.
  
[List of Patents for class 501 subclass 31]    31Uncombined silica containing (e.g., sand):
 This subclass is indented under subclass 27.  Compositions which contain uncombined silica as an ingredient of the batch.
(1) Note. The uncombined silica is typically disclosed to be sand.
  
[List of Patents for class 501 subclass 32]    32Glass and material other than glass (e.g., crystal glass, opal glass, etc.):
 This subclass is indented under subclass 11.  Compositions which contain a glass and at least one ingredient which is not a glass, wherein the nonglass ingredient is not dissolved in the glass.
(1) Note. This subclass includes such materials as, e.g., two phase glasses, opal glass, crystal glass, etc.
(2) Note. Documents classified as originals in this subclass are cross-referenced on the basis of the chemical nature of the glass composition disclosed into subclasses 40, 41+, and/or 53+ as appropriate.
(3) Note. Documents classified as originals in this subclass which disclose optical glass compositions are cross-referenced in subclasses 900+.