Rivestimenti resistenti all'usura per acciaio

Wear resistant coatings for steel are engineered surface layers applied to improve abrasion resistance, resistenza all'erosione, and service life of steel components. Instead of replacing entire structural parts with high-hardness materials, coating technology allows manufacturers to enhance surface performance while maintaining core strength and weldability.

These coatings are widely used in mining, cemento, generazione di energia, produzione di acciaio, e industrie di movimentazione di materiali sfusi.

1. Saldatura di riporti duri (Overlay Welding Process)

Hardfacing is one of the most common manufacturing methods for producing wear resistant coatings.

Process Principle:

A high-alloy welding wire or flux-cored wire is deposited onto a mild steel base plate using arc welding processes. The deposited layer contains high chromium carbides or complex alloy carbides that provide superior hardness.

Metodi di saldatura comuni:

• Saldatura ad arco sommerso (SEGA)

• Saldatura ad arco aperto (OAW)

• Gas Metal Arc Welding (GMAW)

• Saldatura ad arco con filo animato (FCAW)

Caratteristiche:

• Surface hardness: tipicamente 55–65 HRC

• Strong metallurgical bond between coating and base steel

• Suitable for large surface areas

• Customizable overlay thickness (3–20 mm or more)

Applicazioni:

• Chute liners

• Crusher components

• Fan blades

• Cement mill liners

Hardfacing creates a composite wear plate with both structural strength and extreme abrasion resistance.

2. Thermal Spray Coating

Thermal spraying applies molten or semi-molten materials onto a prepared steel surface.

Common Thermal Spray Technologies:

• Plasma spraying

• High Velocity Oxygen Fuel (HVOF)

• Flame spraying

• Arc spraying

Process Steps:

1. Surface preparation (grit blasting for roughness)

2. Heating and accelerating coating material

3. Spraying onto substrate

4. Cooling and finishing treatment

Vantaggi:

• Minimal heat input compared to welding

• Low distortion of base metal

• Suitable for precision components

• Excellent resistance to abrasive and erosive wear

This method is widely used for shafts, rulli, pump parts, and rotating equipment.

3. Laser Cladding

Laser cladding is an advanced surface engineering technology.

Process Description:

A high-energy laser beam melts alloy powder together with a thin layer of the steel substrate, forming a dense metallurgical bond.

Caratteristiche:

• Precise heat control

• Minimal dilution rate

• Low deformation

• Fine microstructure

• Excellent bonding strength

Laser cladding allows accurate control of coating thickness and is suitable for high-value components requiring precision wear resistance.

4. Chromium Carbide Overlay Plate Manufacturing

Rivestimento in carburo di cromo (CCO) plates are produced through automated welding systems.

Manufacturing Process:

• Base plate preparation

• Automated multi-layer weld deposition

• Controlled cooling

• Surface finishing and flattening

The overlay layer contains hard chromium carbides distributed in a martensitic matrix, providing outstanding sliding abrasion resistance.

These plates are commonly fabricated into:

• Fodere per tramogge

• Fodere per trasportatori

• Pipe linings

• Industrial wear panels

5. PTA (Plasma Transferred Arc) Saldatura

PTA welding is a precision hardfacing method used for high-performance coatings.

Process Benefits:

• Low dilution

• Strong metallurgical bonding

• Uniform coating structure

• Excellent wear and corrosion resistance

PTA is commonly applied to:

• Valve seats

• Extruder screws

• Rollers

• Heavy-duty industrial tools

6. Surface Preparation and Quality Control

Regardless of coating method, proper surface preparation is essential:

• Degreasing

• Sandblasting or shot blasting

• Removal of oxides and contaminants

Quality inspection typically includes:

• Test di durezza (HRC or HV)

• Coating thickness measurement

• Ultrasonic testing for bonding integrity

• Visual inspection for cracks or defects

Proper process control ensures durability and consistent coating performance.

7. Selection of Coating Process

Choosing the correct wear resistant coating depends on:

• Tipo di usura (scorrevole, impatto, erosione, or combined)

• Operating temperature

• Required hardness level

• Component geometry

• Budget and production scale

General guidance:

• Large flat structures → Overlay welding

• Precision components → Laser cladding or HVOF

• Severe sliding abrasion → Chromium carbide overlays

• Impatto + abrasion → Alloy hardfacing systems