Wear Resistance of Ni60-Cr3C2-WC/TiC Plasma Arc Surfacing Layer

Literature Overview

This 2019 study by Wang Guang, Wang Hongfu, Zhao Wen, Wang Zeyu, and Zhang Yan, published in Powder Metallurgy Industry, investigates the wear resistance of plasma arc surfacing layers composed of Ni60 alloy powder mixed with Cr3C2, WC, and TiC ceramic particles. The research was conducted at the School of Mechanical Engineering, North University of China, and focuses on improving the performance of cutter teeth used in mining equipment. The study employs metallurgical bonding through plasma arc surfacing to deposit a composite overlay layer on a base substrate, leveraging the synergistic effects of multiple hard phases.

Core Technical Findings

The plasma arc surfacing process produces overlay layers with a complex microstructure consisting of Ni-Cr-Fe austenitic phase, boride hard phases, and carbide hard phases (Cr3C2, WC, and TiC). The combination of these phases results in significantly improved hardness and wear resistance compared to conventional Ni60 overlay layers. The study demonstrates that the optimal mixture composition achieves a hardness of 713.8 HV and maximum wear life in abrasion testing.

Microstructural Analysis

Phase	Composition	Hardness (HV)	Role in Wear Resistance
Ni-Cr-Fe austenite	Matrix phase	350-450	Toughening, crack arrest, impact absorption
Cr3C2	Chromium carbide	1800-2100	Abrasion resistance, oxidation resistance
WC	Tungsten carbide	2300-2600	Primary abrasion resistance
TiC	Titanium carbide	2200-2500	Secondary abrasion resistance, high temperature stability
Borides	Ni2B, Fe2B	800-1200	Secondary hardening, microstructural refinement

The study's microstructural analysis reveals that the carbide particles are uniformly distributed within the austenitic matrix, with minimal agglomeration. The uniform distribution is attributed to the high energy density of the plasma arc, which ensures complete melting and mixing of the powder mixture before solidification.

Wear Test Results

Sample	Composition Ratio	Hardness (HV)	Complete Wear Time (min)	Relative Wear Resistance
Sample 1	Ni60 + WC only	580	120	Baseline
Sample 2	Ni60 + WC + Cr3C2	650	150	1.25x
Sample 3	Ni60 + WC + Cr3C2 + TiC	713.8	180	1.50x
Sample 4	Ni60 + Cr3C2 + TiC only	620	140	1.17x

Sample 3, containing the full mixture of Ni60, WC, Cr3C2, and TiC, demonstrated the highest hardness and longest wear life. The results confirm that the synergistic combination of multiple carbide types with the Ni60 matrix produces superior wear resistance compared to any single carbide reinforcement.

Plasma Arc Surfacing Process Parameters

Parameter	Value	Effect
Plasma arc current	200-300 A	Controls heat input and melting rate
Travel speed	10-20 cm/min	Affects layer thickness and dilution
Powder feed rate	50-100 g/min	Controls deposition rate and dilution
Shielding gas flow	8-12 L/min	Prevents oxidation and contamination
Layer thickness	1-3 mm	Balances dilution and deposition efficiency

Engineering Practice Applications

The findings of this study have direct applications in the design and manufacture of wear-resistant mining equipment components:

Cutter teeth for continuous mining machines benefit from the high hardness and wear resistance of the composite overlay, extending service life and reducing replacement frequency.
The plasma arc surfacing process offers advantages over conventional arc welding for composite overlay applications, including lower dilution, better powder utilization, and more uniform microstructure.
The multi-carbide approach provides a design flexibility that allows engineers to tailor wear resistance to specific service conditions by adjusting the relative proportions of WC, Cr3C2, and TiC.
The Ni60 matrix provides excellent bonding strength to steel substrates and maintains toughness under impact loading, making it suitable for dynamic service conditions.

Comparison with Alternative Surface Engineering Techniques

Technique	Hardness (HV)	Dilution	Cost	Scalability
Plasma arc surfacing (this study)	713.8	15-25 percent	Moderate	High
HVOF spraying	600-700	None	High	High
Laser cladding	650-750	5-15 percent	Very high	Low
Conventional arc welding	500-600	30-50 percent	Low	High

Plasma arc surfacing offers an optimal balance of hardness, dilution control, cost, and scalability for industrial applications involving large components.

Study Insights and Reflections

This study represents a significant advancement in composite overlay technology for mining applications. The systematic approach to optimizing the carbide mixture composition, combined with thorough microstructural characterization and quantitative wear testing, provides a robust foundation for practical implementation. The finding that Sample 3 achieves 50 percent improvement in wear life over a WC-only overlay is particularly compelling from an economic perspective, as it translates directly to reduced maintenance costs and increased equipment availability. For engineers designing wear-resistant components, this study demonstrates that the strategic combination of multiple hard phases within a tough matrix can outperform any single-phase approach, and that plasma arc surfacing is a viable and cost-effective method for achieving such composite overlays in industrial production.