CMI830 Coulometric Coating Thickness Tester

Overview

The CMI830 Coulometric Coating Thickness Tester is a precision benchtop/portable electrolytic thickness measurement system engineered for quantitative, destructive coulometric analysis of metallic coatings on conductive and non-conductive substrates. Based on Faraday’s law of electrolysis, the instrument electrochemically dissolves a precisely defined surface area of coating under controlled current conditions, measuring the total charge required to remove the layer completely. This enables direct calculation of coating thickness with traceable metrological foundation—ideal for quality control in electroplating, finishing, and surface engineering laboratories where regulatory compliance and inter-laboratory reproducibility are critical.

Key Features

• Coulometric principle ensures absolute thickness measurement without empirical calibration dependency—each result derived from fundamental physical constants (Faraday constant, density, valence, atomic weight)
• Simultaneous real-time monitoring of both coating thickness and dissolution potential curve during test—enabling identification of interface transitions in multilayer systems (e.g., semi-bright/bright nickel, Ni/Cu/Fe)
• Dual test aperture options: Ø2.4 mm (B-type sealing ring) and Ø1.7 mm (S-type sealing ring), supporting micro-area analysis on small or contoured parts
• High-resolution detection: 0.01 µm for Au and decorative Cr; 0.1 µm for Cu, Ni, Zn, Sn, Ag, Cd, hard Cr, electroless Ni, and composite stacks (e.g., Cr/Ni/Cu)
• Validated measurement range: 0.1–35 µm at ≤±10% indication error (per ASTM B504, ISO 2177); extended range available with documented uncertainty increase
• Integrated portable data acquisition unit with RS-232 serial interface—designed for stable operation in production-floor environments with EMI mitigation

Sample Compatibility & Compliance

• Substrate compatibility includes ferrous/non-ferrous metals (steel, brass, Al alloys), plastics with conductive metallization, and sintered NdFeB magnets
• Supported coating systems: single-layer (e.g., Ni on Cu), dual-layer (e.g., semi-bright + bright Ni), triple-layer (e.g., Cr/Ni/Cu), and functional composites (e.g., PTFE-Ni)
• Compliant with international standards for coulometric testing: ASTM B504 (Standard Test Method for Measurement of Thickness of Metallic Coatings by the Coulometric Method), ISO 2177 (Metallic Coatings — Measurement of Coating Thickness — Coulometric Method), and GB/T 4957 (Chinese national standard equivalent)
• Designed to support GLP/GMP documentation requirements: full audit trail capability via timestamped data export, operator ID tagging, and raw curve storage in proprietary .cmi binary format

Software & Data Management

• Windows-based CMI-Soft v3.x application provides live graphical display of dissolution current, voltage, and cumulative charge—enabling visual validation of endpoint detection and interfacial stability
• All test records stored with metadata: date/time, operator ID, sample ID, substrate/coating specification, electrolyte lot number, and environmental temperature
• Export formats include CSV (for LIMS integration), PDF (print-ready reports with embedded curves), and XML (compatible with enterprise QA databases)
• Software supports FDA 21 CFR Part 11-compliant configurations when deployed with Windows domain authentication and electronic signature modules
• No cloud dependency—full local data sovereignty; optional encrypted backup to external USB drives or network shares

Applications

• Automotive & motorcycle suppliers: verification of corrosion-resistant Ni/Cr stacks on trim components per OEM specifications (e.g., GMW14872, Ford WSS-M2G173-A2)
• PCB manufacturers: thickness profiling of immersion gold (ENIG), electroless nickel (ENEPIG), and selective tin plating on high-density interconnects
• Aerospace fastener producers: batch validation of cadmium and zinc-nickel coatings per AMS 2400 and ASTM B633
• Sanitaryware & plumbing fixture OEMs: compliance testing of decorative chromium layers against ISO 4525 and EN 1248
• Research institutions: interfacial electrochemical characterization of nanolaminates and gradient alloy coatings using differential dissolution kinetics
• Third-party certification labs: accredited thickness testing for ISO/IEC 17025 scope accreditation under CNAS or UKAS

FAQ

What electrolytes are supplied with the CMI830, and how many tests can be performed per bottle?
Four 120 mL bottles of standardized electrolytes are included—formulated specifically for Cr, Ni, Cu, and Au/Zn systems. Typical usage is 0.8–1.2 mL per test; each bottle supports ~100–150 measurements depending on aperture size and coating thickness.
Can the CMI830 measure coatings on NdFeB magnets without demagnetization risk?
Yes—the low-current, short-duration dissolution protocol (typically <60 seconds per test) generates negligible eddy-current heating and no external magnetic field, preserving magnetic properties per IEC 60404-5.
Is hardware-level calibration traceable to NIST or other national metrology institutes?
While the instrument itself is not individually NIST-traceable, its coulometric measurement principle is fundamentally traceable to SI units (coulomb, kilogram, second). Certified reference materials (CRMs) such as NIST SRM 2134 (Ni-on-Cu) or PTB reference foils may be used for performance verification per ISO/IEC 17025 Clause 6.6.
Does the software support automated pass/fail judgment against user-defined tolerance limits?
Yes—CMI-Soft allows configurable upper/lower specification limits per coating-substrate pair, with color-coded results (green/yellow/red) and automatic flagging of out-of-spec events in summary reports.
Are replacement sealing rings and electrolyte kits available through global distribution channels?
Yes—standardized B-type (Ø2.4 mm) and S-type (Ø1.7 mm) silicone sealing rings, along with electrolyte replenishment kits (250 mL bottled formulations), are stocked by authorized distributors in North America, EU, and APAC regions under part numbers CMI-RING-B, CMI-RING-S, and CMI-ELK-250.