Wear of Carbide Plates with Diamond-like and Micro-Nano Polycrystalline Diamond Coatings during Interrupted Cutting of Composite Alloy Al/SiC

At a Glance

Metadata	Details
Publication Date	2023-12-08
Journal	Journal of Manufacturing and Materials Processing
Authors	E. E. Ashkinazi, Sergey V. Fedorov, Artem Martyanov, Vadim Sedov, R. A. Khmelnitsky
Institutions	Moscow State Technological University, University of Technology
Citations	2
Analysis	Full AI Review Included

Technical Documentation & Analysis: High-Performance MPCVD Diamond Coatings for Abrasive Machining

Executive Summary

This research validates the superior performance of Microwave Plasma Chemical Vapor Deposition (MPCVD) Polycrystalline Diamond (PCD) coatings for high-speed interrupted cutting of highly abrasive Aluminum Matrix Composites (MMC).

Core Achievement: MPCVD Micro-Nanocrystalline Diamond (MCD/NCD) coatings increased tool durability by 300% (4x life) compared to uncoated carbide inserts when milling Al/SiC (18% SiC content) at 800 m/min.
Material Superiority: MCD/NCD coatings demonstrated twice the durability of advanced Diamond-Like Carbon (DLC) coatings (34 m vs. 17 m cutting length).
Mechanism Shift: The high thermal conductivity and chemical inertia of the MPCVD diamond coating effectively suppressed the primary wear mechanism (soft abrasion/cobalt extrusion) prevalent in uncoated carbide tools.
Material Properties: MCD/NCD exhibited superior mechanical properties, including a high Effective Indentation Modulus (EIT = 719 GPa) and high hardness (HV = 2601 Vickers).
Synthesis Method: The successful coating relied on specialized MPCVD techniques involving alternating micro- and nanocrystalline layers, achieved via periodic nitrogen injection, a capability 6CCVD specializes in.

Technical Specifications

The following data points summarize the critical parameters and performance metrics achieved using the MPCVD MCD/NCD coating technology.

Parameter	Value	Unit	Context
Workpiece Material	A390 MMC (Al/SiC)	wt% SiC	18% SiC phase content
Cutting Speed (v_w)	800	m/min	High-speed interrupted milling
Feed per Tooth (F_z)	0.2	mm	-
Cutting Depth (t_w)	1	mm	-
Tool Substrate	H10F Carbide	% Co	10% Cobalt binder
Flank Wear Criterion (h_f)	0.3	mm	Failure threshold
Uncoated Tool Life (L)	8.5	m	Baseline cutting length
DLC Tool Life (L)	17	m	100% increase over uncoated
MCD/NCD Tool Life (L)	34	m	300% increase over uncoated
MCD/NCD Coating Thickness	6	µm	12 alternating micro/nano layers
MCD/NCD Hardness (HV)	2601	Vickers	Indentation Hardness
MCD/NCD Elastic Modulus (EIT)	719	GPa	Effective Indentation Modulus
MCD/NCD Growth Temperature	850	°C	MPCVD synthesis temperature
Diamond Peak Stress	~2	GPa	Elastic compression stress (Raman)

Key Methodologies

The successful application of the MCD/NCD coating relied on precise substrate preparation and controlled MPCVD growth parameters, demonstrating advanced material engineering capabilities.

Substrate Preparation (Cobalt Removal):
- Carbide inserts (H10F, 10% Co) were chemically etched to remove cobalt binder from the near-surface zone, mitigating the catalytic effect of Co which promotes graphite formation.
- Etching utilized Murakami reagent (K₃Fe(CN)₆:KOH:H₂O = 1:1:10) for 10 minutes, followed by Caro acid (H₂SO₄-H₂O₂) for 4 seconds.
Barrier Layer Deposition:
- A tungsten (W) barrier layer, up to 0.5 µm thick, was applied via magnetron sputtering with preliminary ionic assistance.
- Purpose: To prevent undesirable interaction between carbon and cobalt, and to reduce residual thermal stresses due to matching thermal expansion coefficients.
MPCVD Growth (MCD/NCD):
- The coating was grown using a microwave (2.45 GHz) plasma CVD reactor (ARDIS-100).
- Nucleation Layer (Microcrystalline): Grown for 10 minutes in a methane/hydrogen mixture (4% CH₄) at 850 °C to ensure reliable diamond nucleation.
- Multilayer Growth (Micro-Nanocrystalline): A 12-layer film was formed by periodic injection of nitrogen (N₂) gas.
- Purpose: Nitrogen injection ensures the growth of the nanocrystalline fraction, reducing the overall surface roughness and creating the alternating MCD/NCD structure.
- Total Deposition Time: 6 hours, achieving an average growth rate of ~1 µm/h for a total thickness of 6 µm.

6CCVD Solutions & Capabilities

This research confirms that high-quality, engineered MPCVD Polycrystalline Diamond (PCD) is the optimal material solution for high-speed, abrasive machining of MMCs. 6CCVD is uniquely positioned to supply and customize the materials required to replicate and advance this critical research.

Applicable Materials

To achieve the 300% durability increase demonstrated in this study, 6CCVD recommends the following materials:

PCD (Polycrystalline Diamond) - High Thermal Conductivity Grade: Our standard MPCVD PCD is synthesized to maximize thermal conductivity and chemical inertness, essential for suppressing soft abrasion and adhesive wear mechanisms in high-speed aluminum machining.
Custom MCD/NCD Architecture: 6CCVD offers precise control over the MPCVD recipe, including gas flow (CH₄/H₂) and dopants (N₂), allowing for the exact replication or optimization of the alternating micro- and nanocrystalline layer architecture (MCD/NCD) used in this study.

Customization Potential

The success of the MCD/NCD coating was highly dependent on precise thickness control (6 µm) and specialized substrate preparation (W barrier layer). 6CCVD offers comprehensive customization capabilities to meet these exact engineering requirements:

Research Requirement	6CCVD Capability	Specification Range
Custom Thickness	Precise control over MPCVD growth time and rate.	PCD thickness from 0.1 µm up to 500 µm.
Substrate Pre-treatment	Consultation and execution of specialized chemical etching protocols (e.g., Co removal).	In-house expertise for WC-Co substrate preparation.
Barrier Layer Metalization	Internal capability to deposit adhesion-promoting barrier layers.	Custom deposition of W, Ti, Pt, or other metals up to 1 µm.
Custom Dimensions	Supply of large-area PCD plates for tool fabrication or direct coating of inserts.	Plates/wafers up to 125 mm (PCD); Substrates up to 10 mm thick.
Surface Finish	Optimization of surface roughness for reduced friction and sticking.	Polishing available for PCD to Ra < 5 nm (Inch-size).

Engineering Support

The complexity of applying diamond coatings to carbide tools (especially managing the cobalt binder) requires deep material science expertise. 6CCVD’s in-house PhD team specializes in optimizing diamond growth recipes for extreme applications.

Application Focus: We provide expert consultation on material selection and coating architecture for similar high-speed abrasive milling projects involving MMCs, ceramics, and highly reinforced polymers.
Adhesion Optimization: We assist engineers in designing optimal barrier layers and pre-treatment protocols to maximize the adhesive bond strength (critical for preventing chipping) between the PCD film and the WC-Co substrate.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

The complexity of milling metal matrix composite alloys based on aluminum like Al/SiC is due to their low melting point and high abrasive ability, which causes increased wear of carbide tools. One of the effective ways to improve its reliability and service life is to modify the surface by plasma chemical deposition of carbon-based multilayer functional layers from vapor (CVD) with high hardness and thermal conductivity: diamond-like (DLC) or polycrystalline diamond (PCD) coatings. Experiments on an indexable mill with CoroMill 200 inserts have shown that initial tool life increases up to 100% for cases with DLC and up to 300% for multilayered MCD/NCD films at a cutting speed of 800 m/min. The primary mechanism of wear of a carbide tool in this cutting mode was soft abrasion, when wear on both the rake and flank surfaces occurred due to the extrusion of cobalt binder between tungsten carbide grains, followed by their loss. Analysis of the wear pattern of plates with DLC and MCD/NCD coatings showed that abrasive wear begins to prevail against the background of soft abrasion. Adhesive wear is also present to a lesser extent, but there is no chipping of the base material from the cutting edge.

Tech Support

Original Source

DOI: https://doi.org/10.3390/jmmp7060224

References

2022 - Fabrication, microstructure, and machinability of aluminum metal-matrix composites
2023 - A Systematic Review on the Mechanical, Tribological, and Corrosion Properties of Al 7075 Metal Matrix Composites Fabricated through Stir Casting Process
2016 - Studies on Mechanical Properties of Al-SiC Metal Matrix Composite
2016 - Mechanical and Tribological Properties of Centrifugally Cast Al-Si-SiC Composites
2016 - Effects of SiCp Reinforcement on the Abrasive Wear Properties of Al-Si Alloy [Crossref]
2016 - Machining of aluminum alloys: A review [Crossref]
2017 - Machinability and Wear of Aluminium Based Metal Matrix Composites by MQL—A Review [Crossref]
2023 - Study of tool flank wear and surface quality in milling of Al520-MMCs reinforced with SiC and Sn particles