From aerospace to everyday items, why has thermal spray become the "all-rounder" in the coating industry?

author: mia

2025-05-10

Thermal spray heats materials (metal/ceramic/polymer) into molten/semi-molten state, sprays them onto substrates for protective/functional coatings, enhancing durability and insulation in industries like aerospace and automotive.

Thermal Spray Technology: A Versatile Solution in Surface Engineering

In the field of industrial manufacturing and surface engineering, thermal spray technology has become a critical technique for enhancing material surface performance due to its superior properties and wide-ranging applications. This article provides a detailed overview of thermal spray technology, covering its processes, applications, characteristics, and workflows to offer a comprehensive understanding of this advanced technology.

Overview of Thermal Spray Technology

- Process Introduction

Common Types of Thermal Spray in the Market

- Flame Spray

- Arc Spray

- Plasma Spray

- High-Velocity Oxygen-Fuel (HVOF) Spray

Application Scope of Thermal Spray Technology

Characteristics of Thermal Spray Technology

Thermal Spray Process Flow

1. Overview of Thermal Spray Technology

(一) Process Introduction

Thermal spray technology is a technique that heats coating materials to a molten or semi-molten state using a heat source, atomizes them with high-speed gas flow, and sprays them onto a substrate surface to form a coating with specific properties. This process can deposit functional coatings with wear resistance, corrosion resistance, high-temperature resistance, thermal insulation, conductivity, insulation, and other properties on various substrate materials such as metals, ceramics, and plastics. It significantly improves the surface performance of substrates, extends their service life, and expands their application scope.

2. Common Types of Thermal Spray in the Market

(一) Flame Spray

Flame spray uses the heat generated by the combustion of combustible gases (e.g., acetylene, propane) mixed with oxygen to melt spray materials. The molten particles are then propelled onto the substrate surface by high-speed gas flow to form a coating. This method features simple equipment, low cost, and easy operation, but the coatings typically have higher porosity and relatively lower bond strength. It is suitable for applications with moderate coating requirements, such as preparing wear-resistant and corrosion-resistant coatings for general mechanical parts.

(二) Arc Spray

Arc spray generates an electric arc between two charged metal wires, melting the wires, and uses high-pressure gas to atomize and spray the molten metal onto the substrate surface. This method offers high spraying efficiency, relatively high bond strength, and moderate cost. It is widely used for spraying metal coatings like zinc and aluminum in steel structure anti-corrosion applications.

(三) Plasma Spray

Plasma spray utilizes a plasma arc as the heat source, which can reach temperatures exceeding 10,000°C, to melt spray materials at high temperatures. The high-temperature and concentrated energy of the plasma arc enable spraying of high-melting-point materials such as ceramics and cermets. Plasma-sprayed coatings feature excellent quality, low porosity, and high bond strength, making them ideal for producing high-performance high-temperature and wear-resistant coatings in aerospace, engines, and other critical fields.

(四) High-Velocity Oxygen-Fuel (HVOF) Spray

HVOF spray uses the high-speed gas flow (several times the speed of sound) generated by the combustion of fuels (e.g., kerosene, hydrogen) and oxygen to heat and accelerate spray materials onto the substrate surface. This process is renowned for producing dense coatings with extremely high bond strength and wear resistance, particularly suitable for spraying tungsten carbide and other hard alloy coatings. It is widely applied in surface strengthening of precision components such as cutting tools and molds.

3. Application Scope of Thermal Spray Technology

Thermal spray technology is widely used across numerous industries and fields:

Aerospace Industry: Prepares high-temperature-resistant coatings for aircraft engine blades and anti-corrosion coatings for airframe structures, enhancing component performance and reliability in harsh high-temperature, high-pressure environments.

Automotive Manufacturing: Sprays engine blocks, piston rings, valves, and other parts to improve wear and corrosion resistance, extending engine life; also used for anti-corrosion coatings on vehicle chassis.

Electronics and Electrical Industry: Deposits insulating, conductive, or heat-dissipating coatings on electronic components to meet functional requirements, such as insulating coatings for PCBs and heat-dissipating coatings for heat sinks.

Energy and Power Industry: Applies wear- and corrosion-resistant coatings to boiler pipes, steam turbine blades, and other equipment in thermal power plants, improving their service life in high-temperature, high-pressure, and high-dust environments; also crucial for surface anti-corrosion treatment of wind power equipment in the new energy sector.

Medical Device Industry: Sprays biocompatible coatings (e.g., hydroxyapatite) on medical implants to promote bone cell growth and improve implant compatibility and stability.

Mechanical Manufacturing: Repairs worn mechanical parts (e.g., shafts, gears, bearings), restoring their dimensions and performance, reducing maintenance costs, and minimizing part replacement frequency.

4. Characteristics of Thermal Spray Technology

(一) Enhanced Surface Performance

Capable of producing coatings with diverse functions (e.g., wear resistance, corrosion resistance, high-temperature resistance, thermal insulation) to significantly improve substrate surface performance and meet the demands of various working conditions.

(二) Wide Material Selection

Supports a vast range of spray materials, including metals, alloys, ceramics, plastics, and composites—virtually covering all solid engineering materials—to provide flexible solutions for different applications.

(三) Controllable Coating Thickness

Coating thickness can be flexibly adjusted from a few micrometers to several millimeters, adapting to the requirements of different parts, whether for thin-walled or thick-walled components.

(四) Process Flexibility

Applicable to substrates of various shapes and sizes, including flat, curved, and internal surfaces, with minimal restrictions on substrate geometry, making it suitable for surface treatment of complex components.

(五) Cost-Effectiveness

For valuable or critical parts, surface strengthening or repair through thermal spray technology extends service life, avoiding overall replacement and thus reducing costs and improving economic efficiency.

5. Thermal Spray Process Flow

(一) Substrate Preparation

A crucial preliminary step to ensure a clean and rough substrate surface for improved coating adhesion, including:

Cleaning: Removes contaminants such as oil, grease, and oxides using methods like solvent cleaning or ultrasonic cleaning.

Surface Roughening: Creates surface roughness through sandblasting (using materials like quartz sand or alumina) or grinding to enhance mechanical bonding between the coating and substrate.

(二) Equipment Calibration

Adjusts parameters of thermal spray equipment (e.g., heat source temperature, gas flow rate, spraying distance, powder feeding rate) according to the spray material and process requirements to ensure optimal equipment performance.

(三) Spraying Operation

Fixes the pre-treated substrate on the spraying equipment, activates the equipment to melt/soften the spray material via the heat source, and atomizes it with high-speed gas flow to deposit a uniform and continuous coating on the substrate surface.

(四) Post-Processing

Performs necessary post-treatments based on coating requirements, such as grinding/polishing to improve surface precision and finish, or sealing/heat treatment to enhance bond strength and reduce porosity.

As a key technology in surface engineering, thermal spray technology plays an increasingly important role in industrial manufacturing and various industries, thanks to its diverse types, wide applications, unique characteristics, and scientific process flow. With continuous technological development and innovation, thermal spray technology will continue to enhance coating performance, expand application frontiers, and provide stronger support for high-end manufacturing and emerging industries.

Dongguan Sanlixin Plastic Technology Co.,Ltd

Shenzhen Sanlixin Technology Co., Ltd. and Dongguan Sanlixin Plastic Technology Co., Ltd. is a manufacturer integrating precision plastic mold design, mold opening, single (double) color injection molding, IML injection molding processing, producing various single (double) color, IML process high-end appearance decorative structural parts, two-color buttons, USB dust plugs, panels and other plastic products, providing customers with fast, excellent, Midea all-round service, the company has 15 years of experience in precision plastic mold design, processing and production, with a variety of advanced machine injection molding equipment with excellent quality and fast service to win the trust and strong support of our customers.