Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D1082-17 – Standard Test Method Technical Guide
📏 Scope and Specimen Thickness
This test method, formally designated as ASTM D1082–17 (Reapproved 2024), covers the determination of the dissipation factor and relative permittivity of natural muscovite mica. The standard applies to two distinct material categories defined specifically by their thickness:
| 🟦 Material Type | 📏 Thickness (in.) | 📐 Thickness (mm) |
|---|---|---|
| Natural Block Mica | 0.007 to 0.030 | 0.18 to 0.77 |
| Mica Films / Capacitor Splits | 0.0008 to 0.004 | 0.02 to 0.10 |
It is critical to note that the values stated in inch-pound units shall be regarded as the standard. The metric values provided in parentheses are for informational purposes only.
⚠️ Safety Advisory: This standard does not address all safety concerns associated with its use. The user is responsible for establishing appropriate safety, health, and environmental practices and for determining the applicability of regulatory limitations prior to use. A specific warning is given in Section 7 and Section 6.1.1 of the standard.
⚙️ Test Method and Apparatus Requirements
Any of the techniques and apparatus outlined in ASTM D150 (Test Methods for AC Loss Characteristics and Permittivity of Solid Electrical Insulation) are suitable for measuring the dissipation factor and relative permittivity of mica. An appropriate electrode system must be selected from the options provided in Section 5 of this test method.
If only a relative order of magnitude of the dissipation factor is required, the specific Method A provided in the Appendix of ASTM D748 (Specification for Natural Block Mica and Mica Films) is considered satisfactory for this purpose.
| 📄 Referenced Document | ⚡ Description |
|---|---|
| ASTM D150 | AC Loss Characteristics and Permittivity |
| ASTM D374 | Thickness of Solid Electrical Insulation |
| ASTM D748 | Specification for Natural Block Mica |
| IEC 60371-2 | Methods of test for mica-based materials (procedures differ from this standard) |
💡 Important Deviation Note: While IEC Publication 60371-2 covers procedures for the measurement of dissipation factor and permittivity, the technical details of its procedure are somewhat different from those specified in this ASTM test method (see Note 1 in the standard). Adherence to the D1082 protocol is required for specification compliance.
📊 Significance of Key Measured Properties
Dissipation Factor: This property is of practical importance as a direct measure of the electrical energy lost as heat within the mica dielectric. It is particularly critical in applications where the electric field is applied perpendicular to the plane of cleavage, such as in fixed mica-dielectric capacitors. Its measurement is essential for specification acceptance and dielectric-loss control at radio frequencies and specific audio frequency applications.
Relative Permittivity (Dielectric Constant): This property measures the ability of mica to store electrostatic energy. For natural muscovite mica, the relative permittivity perpendicular to the cleavage plane is fairly uniform, regardless of the mica’s origin. This makes it valuable primarily for material identification, advanced research, design calculations, and special application evaluation where the loss index is required.
❓ Frequently Asked Questions
🔍 What is the standard unit of measurement in D1082?
The values stated in inch-pound units are to be regarded as the standard for this test method. Values provided in parentheses (metric/SI) are for informational purposes only.
💡 What is the practical significance of the dissipation factor?
It measures the electrical energy lost as heat in the mica serving as a dielectric substance. This is critically important in capacitors and applications using mica at radio frequencies.
⚡ What thickness range applies to mica films and splits?
Mica films or capacitor splits are defined as having thicknesses between 0.0008 and 0.004 in. (0.02 and 0.10 mm).
📌 Which main standard provides the general apparatus for this test?
This test method designates ASTM D150 (Test Methods for AC Loss Characteristics and Permittivity of Solid Electrical Insulation) for suitable techniques and apparatus, with specific electrode system selection guidelines provided in Section 5 of D1082.