Optimized Hot Pressing of High-Speed Steel–Bronze Composites for Diamond-Reinforced Tool Applications

At a Glance

Metadata	Details
Publication Date	2025-08-26
Journal	Materials
Authors	Filip Průša, A. Romański, M. Książek, Hana Thürlová, Dorota Tyrała
Institutions	University of Chemistry and Technology, Prague, AGH University of Krakow
Analysis	Full AI Review Included

Technical Documentation & Analysis: Optimized Diamond-Reinforced Composites

Executive Summary

This research successfully optimized the hot-pressing parameters for ASP60 high-speed steel (HSS) composites using CuSn20 bronze as a liquid-phase sintering aid, specifically targeting diamond-reinforced tools for aggressive stone-cutting applications.

Porosity Reduction: The addition of 9.8 wt.% CuSn20 bronze significantly reduced residual porosity to a minimum of 3.70% at the optimal compaction temperature of 1050 °C, enhancing densification and mechanical integrity.
Mechanical Performance: The optimized matrix achieved a high bending strength of 374.51 ± 36.73 MPa, demonstrating superior mechanical properties compared to pure ASP60 compacts.
Thermal and Tribological Stability: CuSn20 acts as a self-lubricating agent, consistently lowering the friction coefficient across all tested temperatures (25 °C to 800 °C). The composite matrix exhibits zero measurable wear.
High Operating Potential: The resulting composite matrix shows potential for operating temperatures up to 750 °C, exceeding the thermal limits of many current commercial matrices.
Diamond Reinforcement: The composite was successfully reinforced with TiC-coated synthetic diamond grits (60/80 mesh), although the study noted localized flaws in the commercial TiC coating, highlighting the need for superior coating integrity.
Processing Limitation: The use of uniaxial hot pressing resulted in heterogeneous pore distribution, suggesting that advanced consolidation methods (e.g., HIP) or high-purity, pre-sintered diamond materials are necessary for full-density components.

Technical Specifications

The following hard data points were extracted from the optimization and testing phases of the ASP60-CuSn20 composite:

Parameter	Value	Unit	Context
Optimal Compaction Temperature	1050	°C	Hot Pressing (Uniaxial)
Final Compaction Pressure	35	MPa	Applied for 3 min dwell time
Optimal CuSn20 Content	9.8	wt.%	For minimal porosity
Minimal Residual Porosity (Matrix)	3.70 ± 0.01	%	Archimedes method (ASP60 + CuSn20 at 1050 °C)
Maximum Bending Strength (Matrix)	374.51 ± 36.73	MPa	ASP60 + CuSn20 at 1050 °C
Composite Bending Strength	359.1 ± 26.5	MPa	Reinforced with TiC/Diamond (c = 20)
Diamond Grit Size	60/80	Mesh	Synthetic, TiC-coated
Diamond Concentration	20 (1 carat/cm³)	c	Reinforcement level
Vickers Hardness (HV30, Crack Site)	906.0 ± 18.5	HV30	ASP60 + CuSn20 at 1050 °C
Rockwell Hardness (HRC, Crack Site)	64.8 ± 0.4	HRC	ASP60 + CuSn20 at 1050 °C
CuSn20 Partial Melting Onset	~778	°C	Peritectic reaction, enhancing self-lubrication
Potential Operating Temperature	Up to 750	°C	For the optimized matrix composition

Key Methodologies

The composite materials were fabricated and characterized using the following primary steps:

Powder Preparation: Water-atomized ASP60 HSS powder and gas-atomized CuSn20 bronze powder were selected.
Powder Characterization: Detailed analysis included X-ray diffraction (XRD), X-ray fluorescence (XRF), differential scanning calorimetry (DSC), SEM, and laser diffraction (ASP60 D₅₀ = 62.0 µm; CuSn20 D₅₀ = 22.8 µm).
Hot Pressing Parameters:
- Temperatures Tested: 950 °C, 1000 °C, and 1050 °C.
- Pressure Profile: Staged application: 15 MPa (up to 750 °C), 20 MPa (above 750 °C), and 35 MPa (final dwell).
- Dwell Time: 3 minutes at final temperature.
Reinforcement: Synthetic diamond grits (60/80 mesh) pre-coated with a Titanium Carbide (TiC) layer were incorporated at a concentration of c = 20 (1 carat/cm³).
Mechanical Testing: Three-point bending tests were performed using a 10kN sensor. Hardness was measured using Vickers (HV30) and Rockwell (HRC) methods on both tensile and compressive sides.
Tribological Assessment: Ball-on-disc testing (Al₂O₃ ball, 5 N load, 0.5 mm/s) was conducted at 25 °C, 300 °C, 500 °C, and 800 °C to evaluate temperature-dependent friction coefficients.

6CCVD Solutions & Capabilities

The research highlights the critical need for high-integrity diamond reinforcement and advanced consolidation techniques to maximize tool performance in extreme environments. 6CCVD is uniquely positioned to supply the necessary materials and engineering support to replicate and advance this research.

Applicable Materials

The study utilized TiC-coated synthetic diamond grits. 6CCVD offers superior diamond materials that can be tailored for this application:

Research Requirement	6CCVD Solution	Material Advantage
High Wear Resistance	Polycrystalline Diamond (PCD) Plates	Plates/wafers up to 125mm in size, offering robust, large-area reinforcement for stone-cutting segments.
Thermal Stability/Coating	Single Crystal Diamond (SCD) Wafers	High-purity SCD (thickness 0.1µm - 500µm) provides intrinsic thermal stability and can be custom-coated internally.
Matrix Integration	Custom Metalized Diamond	We offer internal metalization capabilities (Ti, W, Cu, Pt, Au, Pd) to ensure optimal chemical bonding and thermal barrier integrity, addressing the coating flaws observed in the paper’s commercial grits.
Conductivity/Heat Dissipation	Boron-Doped Diamond (BDD)	For applications requiring enhanced thermal conductivity or electrochemical properties, BDD substrates (up to 10mm thick) are available.

Customization Potential

The paper noted that uniaxial pressing led to heterogeneous porosity and that the commercial TiC coating had flaws, compromising the diamond’s protective barrier. 6CCVD’s custom fabrication services directly address these limitations:

Custom Dimensions and Geometry: While the paper used 40 mm long prisms, 6CCVD can supply PCD plates up to 125 mm in diameter or custom-cut SCD/PCD inserts to precise specifications required for wire sawing or segment tools.
Advanced Surface Preparation: We offer ultra-smooth polishing (Ra < 1nm for SCD, Ra < 5nm for inch-size PCD), ensuring optimal interface quality prior to matrix consolidation.
High-Integrity Metalization: 6CCVD provides in-house Ti metalization (as well as W, Cu, Pt, Au, Pd) via advanced deposition techniques, guaranteeing uniform and defect-free protective layers crucial for suppressing graphitization and enhancing matrix adhesion during high-temperature hot pressing (1050 °C).

Engineering Support

The challenges faced in this research—specifically optimizing the diamond-matrix interface and overcoming consolidation heterogeneity—are core areas of 6CCVD’s expertise.

Interface Engineering: Our in-house PhD team specializes in high-pressure/high-temperature (HPHT) and MPCVD diamond synthesis and processing. We provide consultation on selecting the optimal diamond material (SCD vs. PCD) and metalization scheme (e.g., Ti/W/Cu multilayer systems) to maximize bonding strength and thermal stability in aggressive stone-cutting applications.
Consolidation Strategy: We assist engineers in transitioning from uniaxial pressing limitations (heterogeneous porosity) to utilizing high-quality, pre-sintered diamond components that minimize reliance on liquid-phase sintering aids for densification.
Global Supply Chain: 6CCVD ensures reliable, global shipping (DDU default, DDP available) of high-value diamond materials, supporting continuous research and production cycles worldwide.

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

View Original Abstract

This study investigates the optimization of hot-pressing parameters for ASP60 high-speed steel composites incorporating CuSn20 bronze alloy for use in diamond-reinforced tool applications. ASP60 and CuSn20 powders were characterized using XRD, XRF, DSC, SEM, and laser diffraction. The effects of CuSn20 addition at varying concentrations and compaction temperatures (950-1050 °C) on porosity, mechanical properties, and tribological performance were evaluated. Results showed that adding CuSn20 significantly reduced residual porosity due to its partial melting during compaction, which facilitated particle rearrangement and densification. Optimal conditions were identified at 1050 °C with 9.8 wt.% CuSn20, yielding minimal porosity (~3.7%) and the highest bending strength (374.51 ± 36.73 MPa). The optimized matrix was further reinforced with TiC-coated diamond particles at concentration c = 20, producing a composite material with excellent wear resistance, despite minor defects in the TiC coating observed on fracture surfaces. Tribological testing demonstrated that CuSn20 consistently lowered friction coefficients across all tested temperatures due to its self-lubricating properties and partial melting at elevated temperatures. Furthermore, ASP60 exhibited no measurable wear, making it a promising candidate for highly demanding applications. Overall, the study demonstrates that CuSn20 alloy enhances densification, mechanical performance, and tribological behavior of ASP60-based composites, indicating their strong potential for aggressive wire sawing and stone-cutting tool applications.

Tech Support

Original Source

DOI: https://doi.org/10.3390/ma18173999

References

2020 - The manufacturing and the application of polycrystalline diamond tools—A comprehensive review [Crossref]
2001 - Consolidation of diamond tools using Cu-Co-Fe based alloys as metallic binders [Crossref]
2018 - Investigating the effect of brazing parameters on joint quality in DIN 2391 steel material and natural stone cutting core sockets joined by using induction brazing method [Crossref]
2024 - Improving wear resistance and machining performance of diamond tools in ferrous metals cutting: A review [Crossref]
2025 - Wear mechanisms of diamond tools and their material basis in machining iron-based materials [Crossref]
2018 - New Diamond-Based Superhard Materials. Production and Properties. Review [Crossref]
2020 - A critical review on the chemical wear and wear suppression of diamond tools in diamond cutting of ferrous metals [Crossref]
2025 - Comparative study of brazing granite/marble diamond segments for applications in decorative stone cutting machines: Microstructural and microhardness characterization with Cu/Ag-based filler metals [Crossref]