Standard No.:	GB/T 39482.1-2023
English Name:	Electrochemical impedance spectroscopy (EIS) on coated and uncoated metallic specimens—Part 1：Terms and definitions
Chinese Name:	涂漆和未涂漆金属试样的电化学阻抗谱（EIS） 第1部分：术语和定义
Chinese Classification:	G50    Basic standard and general method for coating
Professional Classification:	GB    National Standard
Source Content Issued by:	SAMR; SAC
Issued on:	2023-09-07
Implemented on:	2024-4-1
Status:	valid
Target Language:	English
File Format:	PDF
Word Count:	7500 words
Translation Price(USD):	230.0
Delivery:	via email in 1~3 business day

GB/T 39482.1-2023 Electrochemical impedance spectroscopy (EIS) on coated and uncoated metallic specimens - Part 1: Terms and definitions 1 Scope This document defines terms for electrochemical impedance spectroscopy (EIS) for use in the other parts of GB/T 39482. 2 Normative references There are no normative references in this document. 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 peak-to-peak amplitude 2U0 maximum value between maximum and minimum excitation of the applied a.c. perturbation signal Note: The peak-to-peak amplitude is usually expressed in millivolts. 3.2 rms amplitude Urms root-mean-square (i.e. effective) value of the applied a.c. perturbation signal Note: This is the peak-to-peak value of the a.c. amplitude, divided by 2 x . 3.3 Bode plot curves of (a) phase angle (3.36) versus the logarithm of the applied frequency and (b) the logarithm of the magnitude of the impedance (3.28) |Z| versus the logarithm of the applied frequency 3.4 charge transfer resistance Rct resistance of the resistor representing the metal-electrolyte interface characteristics in the equivalent circuit (3.18) Note: The charge transfer resistance is usually expressed in ohms. The specific charge transfer resistance is usually expressed in ohms times square centimetres. 3.5 coating layer formed from a single or multiple application of a coating material to a substrate [SOURCE: ISO 4618:2014, 2.50.1] 3.6 coating process of applying a coat Note: The use of the term “coating” for “coating material” is deprecated. [SOURCE: ISO 4618:2014, 2.50.2] 3.7 coating capacitance Cc capacitance of the capacitor representing the electrical capacitance of the coating (3.5) in the equivalent circuit (3.18) Note 1: The coating capacitance is usually expressed in nanofarads. The specific coating capacitance is usually expressed in nanofarads per square centimetre. Note 2: For coatings which do not have ideal capacitance, the constant phase element (CPE) is frequently used. The use of a constant phase element does not have a physical meaning. 3.8 coating resistance Rc resistance (3.40) of the resistor representing the electrical resistance of the coating (3.5) in the equivalent circuit (3.18) Note: The coating resistance is usually expressed in gigaohms. The specific coating resistance is usually expressed in gigaohms times square centimetres. 3.9 corrosion potential Ucor potential of a corroding surface at which the rate of oxidation (corrosion) and the rate of reduction of the one or more oxidants are equal Note 1: This is also known as the mixed potential or the rest potential. Note 2: This potential is measured relative to a reference electrode (3.39) under open-circuit conditions. Note 3: The corrosion potential is usually expressed in volts. 3.10 corrosion rate amount of metal lost in unit time Note: The corrosion rate is usually expressed in millimetres per year. 3.11 counter electrode; CE inert electrode in the electrochemical cell (3.15) through which the current passes from or to the working electrode (3.46) 3.12 double-layer capacitance Cdl capacitance of the capacitor representing the metal-electrolyte interface characteristics in the equivalent circuit (3.18) Note: The double-layer capacitance is usually expressed in microfarads. The specific double-layer capacitance is usually expressed in microfarads per square centimetre. 3.13 dummy cell printed-circuit board with mounted electrical components representing the equivalent circuit (3.18) and with connection points to the measuring instrument 3.14 electrical zero-reference voltage with respect to which all voltages within the electrochemical equipment are referenced 3.15 electrochemical cell system consisting of at least two electrodes in an electrolyte 3.16 electrochemical impedance spectroscopy; EIS electrochemical technique which allows the impedance spectrum of an electrochemical system to be recorded as a function of the frequency of the applied signal, and the spectrum thus obtained to be analysed by transfer function analysis 3.17 electromagnetic noise electrical noise in the current and/or voltage signal in a circuit whose origin is stray electromagnetic radiation from nearby electrical devices 3.18 equivalent circuit electrical circuit modelling the impedance (3.23) of the specimen under test Note: For example, this could be a network, consisting of elements such as a resistor, a capacitor and an inductor, which has the same impedance spectrum (i.e. the same response to a perturbation) as the electrochemical system. 3.19 error estimate percentage deviation from zero of the recorded data, or the percentage deviation of the data from the absolute values of the elements of the dummy cell used Note 1: The percentage deviation from zero of the recorded data is determined by subtracting the data from the theoretical equivalent-circuit data and dividing it by the latter. This method is only suitable for dummy cell measurements. Note 2: The percentage deviation from the absolute values of the elements of the dummy cell used is determined by calculating the values of the equivalent-circuit elements from the recorded spectra. It is expressed as the percentage deviation from the absolute values of the elements of the dummy cell. 3.20 Faraday cage metallic cabinet, used to reduce electromagnetic interference to the electrochemical cell (3.15) (or circuit), that completely encases the cell and is grounded to the instrument earth 3.21 galvanostat electronic instrument which controls the current through the working electrode (3.46) and counter electrode (3.11) and which measures the resulting potential at the working electrode with respect to a reference electrode (3.39) 3.22 ground electronic reference point Note: Voltage in the circuit is measured with respect to this reference point. In an electrochemical system, there could be several types of ground: a) Earth ground, which is a connection to earth. The “protective ground pin” in a.c. receptacles is connected to earth. The chassis of a desktop computer connected to the a.c. mains will be grounded in this way. b) Floating ground, which in an electrochemical system (instrumentation and cell) is one which is not actually connected to earth. c) Signal ground, which is the reference point in the electronic circuit of a potentiostat (3.38). A signal ground can be earthed or floating, depending upon the potentiostat design. d) Virtual ground, which is a point, generally the working electrode (3.46), maintained at a voltage equivalent to ground by an operational amplifier. 3.23 impedance Z frequency-dependent, complex-number proportionality factor, ΔU/ΔI, between the applied alternating current voltage U (or current I) and the response current (or potential) in an electrochemical cell (3.15) Note 1: This factor is the impedance only when the perturbation and response are linearly related (the value of the factor is independent of the magnitude of the perturbation) and the response is caused only by the perturbation. The value of the impedance can be related to the corrosion rate (3.10) when measurement is made at the corrosion potential (3.9).