1、Designation:D 2757 86(Reapproved 1999)Standard Specification forImpervious Steatite Ceramics for Electrical and ElectronicApplications1This standard is issued under the fixed designation D 2757;the number immediately following the designation indicates the year oforiginal adoption or,in the case of
2、revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This specification covers the requirements for impervi-ous steatite ceramics having low electrical lo
3、ss characteristicsfor use in electronic and electrical applications.1.2 Impervious steatite ceramics described in this specifica-tion shall be designated as Type I,Type II,Type III,and TypeIV.1.3 The values stated in inch-pound units are to be regardedas the standard.2.Referenced Documents2.1 ASTM S
4、tandards:C 20 Test Methods for Apparent Porosity,Water Absorp-tion,Apparent Specific Gravity,and Bulk Density ofBurned Refractory Brick and Shapes by Boiling Water2D 116 Test Methods for Testing Vitrified Ceramic Materialsfor Electrical Applications3D 150 Test Methods for A-C Loss Characteristics an
5、dPermittivity(Dielectric Constant)of Solid Electrical Insu-lation3D 2520 Test Methods for Complex Permittivity(DielectricConstant)of Solid Electrical Insulating Materials at Mi-crowave Frequencies and Temperatures to 1650C4E 18 Test Methods for Rockwell Hardness and RockwellSuperficial Hardness of M
6、etallic Materials53.Description of Term Specific to This Standard3.1 impervious steatite ceramicssteatite ceramics show-ing no perceptible dye penetration when tested in accordancewith Method C of Test Methods D 116.4.Electrical Requirements4.1 Impervious steatite ceramics shall conform to the elec-
7、trical requirements specified in Table 1.5.Dimensional Requirements5.1 The general dimensional tolerances listed below are tobe considered standard for most unground steatite ceramics,particularly those of simple geometry and good symmetry.Tolerances differing from these should be specified on the p
8、artdrawing.Grinding and other finishing operations permit closerdimensional tolerances.5.1.1 Unglazed Surfaces61%,but not less than 60.005in.(0.127 mm).5.1.2 Glazed Surfaces62%but not less than 60.012 in.(0.305 mm).5.1.3 Angular Dimensions62.5.1.4 Parallelism will be considered satisfactory if theth
9、ickness measured at any point is within the dimensionaltolerance.5.1.5 Ellipticity for deviation from a true circle,will beconsidered satisfactory with a value of 1.02 when the wallthickness is 12%,or more,of the outside diameter.A maxi-mum value of 1.03 will be permitted for a wall thickness of10%o
10、f the outside diameter(see Annex A1).5.1.6 Concentricity,shall be expressed as a deviation ofcenters of a cylinder.Normally a total dial indicator reading of1%of the outside diameter or 0.010 in.(0.254 mm),which-ever is larger,will be permitted where all diameters are eitherall ground or all ungroun
11、d(see Annex A1).5.1.7 Camber,shall be expressed as the ratio between arcand the maximum length of the part.A maximum camber of0.006 in./in.(0.152 mm)of length is permitted unless other-wise specified(see Annex A1).6.Visual Requirements6.1 Parts shall be uniform in color and texture.Visibledefects,su
12、ch as pits,chips,cracks,and blisters,shall not bepermitted to the extent that the life and usefulness of theceramic is impaired.Normal quality will allow defects up to0.031 in.(0.8 mm)unless otherwise specified.7.Handling7.1 All parts shall be handled,inspected,and packaged insuch a manner as to avo
13、id contamination and to prevent contact1This specification is under the jurisdiction of ASTM Committee C-21 onCeramic Whitewares and Related Products and is the direct responsibility of C21.03on Test Methods for Whiteware Properties.Current edition approved Oct.31,1986.Published December 1986.Origin
14、allypublished as D 2757 68 T.Last previous edition D 2757 86(1994)e1.2Annual Book of ASTM Standards,Vol 15.01.3Annual Book of ASTM Standards,Vol 10.01.4Annual Book of ASTM Standards,Vol 10.02.5Annual Book of ASTM Standards,Vol 03.01.1Copyright ASTM,100 Barr Harbor Drive,West Conshohocken,PA 19428-29
15、59,United States.NOTICE:This standard has either been superseded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.with contaminants,particularly metals.8.Physical Requirements8.1 Impervious steatite ceramics shall conform to the physi-c
16、al requirements specified in Table 2.9.Keywords9.1 camber;ceramic;concentricity;electrical insulation;electronic insulation;ellipticity;impervious steatite ceramics;steatiteANNEX(Mandatory Information)A1.DIMENSIONAL CHARACTERISTICSA1.1Ellipticity,shall be determined by dividing the maxi-mum diameter by the minimum diameter measured in the sameplanes,perpendicular to the axis.A1.2 Concentricity,expressed as a displacement of centers,describes the relationship of one diameter to another,both ofwhi
