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SURFACE TREATMENT (METAL)

INTRODUCTION

• Physical/Chemical process or treatment used on the layer surface of materials for enhancement of

Appearance: Color, Pattern, Logo, Shininess etc.

Texture: Roughness, Quality etc.

Feature: Hardening, Anti-Fingerprint, Anti-Scratch

Types of treatment

Anodizing

Coating – PVD, Powder

Plating – Electroplating

Etching MICRO-ARC OXIDATION

Micro-arc Oxidation

ANODIZING

• Use of electrochemical principle • Generate a layer of Al2O3 (alumina) film on the surface of aluminum

and its alloys. • Usually refers to sulfuric acid anodizing oxidation.

INTRODUCTION

PURPOSE

• To form a layer of aluminum oxide and protect the aluminium layer for,

Improved resistance towards wear and corrosion. Enhance the appearance and hardness. Promote paint adhesion. Increased and enhance capacitance in electronic appliances.

ANODIZING

Pre-treatment Anodizing Post-treatment

Pre-treatment

• To improve the surface of metal before anodization takes place

• Include: • Degreasing: To remove any fabrication oils or buffing

compounds • Polishing: To produce smooth math gloss aluminium

surface • Washing: To clean the surface from any heavy metal

hydroxide

Anodizing

• To form anodic oxide layer on the surface of aluminium • Continuous process and stop when desired thickness of layer is

achieved • Include:

• Electrolyte bath, usually sulfuric acid • Anode: Metals to be treated • Cathode: Aluminium or lead

ANODIZING

• Coloring • Integral color: Impart the color during anodizing bath take

place and provide more resistance on abrasion • Electrochemical color: The color is imparted after it is formed

where the coatings is porous and capable of absorbing the color

• Sealing • To seal the pores of the oxide layer • To increase the resistance towards corrosion • To reduce wettability • Ways of sealing: Hydrothermal, Cold impregnation or both

ANODIZING

APPLICATION

Automotive Industry

Medical Equipment

Marine Industry

Aviation & Aerospace

Electronics

Home furnishing

Pros Cons

Durable over time Limited color selection

Easy to maintain

Easy fabrication

Color sustainability

PROS & CONS

ANODIZING

• Processes in which a material is converted to its vapor phase in a vacuum chamber and condensed onto substrate surface as a very thin film.

• Used to produce or deposit thin film technology that carried out under high vacuum and at temperature of 150°C to 500°C.

• Type of PVD coating: • Evaporative deposition • Electron beam vaporization • Pulse laser deposition • Sputter deposition

PVD COATING

INTRODUCTION

Evaporation Transportation Reaction Deposition

PURPOSE

• To improved hardness and wear resistance • To reduced friction • To enhance the oxidation resistance

PROCESS

• Evaporation : Target consisting materials to be deposited is

bombarded with high energy source of ions/electrons beam. Causing dislodge of atoms from the surface of the target and the target vaporized.

• Transport: Movement of vaporized atoms to the substrate for coatings.

• Reaction: Target will react with the gas during transportation process.

• Deposition: Process of build up the coatings on the surface of substrate.

PVD COATING

PVD COATING

Electron beam deposition system

Pulse laser deposition system

Sputter deposition system

PROS & CONS

Pros Cons

• Can be used for almost any type of inorganic and organic materials

• High capital cost

• Environmental friendly process • Rate of coating deposition is slow

• Top coats are not necessary required

• Need cooling system as process require large amount of heats • Good strength and durability

APPLICATION

Aerospace Automotive

Surgical/Medical Dies and molds for materials processing

Cutting tools Fire arms

PVD COATING

POWDER COATING

• Use electrostatic Spray Machine to coat the powder to the surface of metals. The electrostatic powder is evenly adsorbed on the surface to form powder coating.

• High temperature coatings leads to the coatings to solidified as different types of powder coatings is used.

Pre-Treatment

Powder Coating

Oven Curing

Packaging

INTRODUCTION

PROCESS

Pre-treatment: Process to prepare the aluminum for coatings. Successful adhesion of powder to the aluminum is dependent upon the quality of pre-treatment.

Powder coating: Consist thermoset resins, pigment & additives where it is applied to the metal surface using powder coating gun or electrostatic spray gun.

Oven curing: Painted products are cured using oven baking. The powder liquefies and the resin cross link producing tough and durable surface finish.

Packaging: Prevent marking of finished surface of metals.

Pros Cons

• Rich in color • The usage in electronic products is low • Low cost which suitable for

furniture

• High utilization rate and have shielding defect ability

PROS & CONS

APPLICATION

Architectural Automotive Household equipment

POWDER COATING

POWDER COATING

Powder coating unit with electrostatic spray

guns

Drying/curing oven

ELECTROPLATING

• It is involve the passing of electric current through electrolyte solution, electrodes and power supply.

• It is also known as electro deposition process where it is involves deposition of thin later of metal onto the work piece surfaces (substrate).

INTRODUCTION

PURPOSE

• To increase the thickness of metal surface.

• To enhance the wear resistance properties.

• To improve the electrical conductivity of metals

Pre-Treatment Electroplating Finishing

PROCESS

Pre-treatment • Cleaning: Include the stripping process where removal of plating or

paint is done. It is done by dipping the electrode into strong acid or alkaline briefly to remove all the impurities.

Electroplating • Need metal that can conduct electricity. • Anode is plating metal while cathode is the target to be treated. • Both electrode is immersed in the solution which containing the ions

and when power is switch on, the ions from anode will be dissolve in the solution and deposited onto the cathode electrode.

• This will formed a thin layer of metal plate at the cathode.

Finishing

• Chemical rinsing: To make the metals more resistance towards corrosion.

• Water rinsing: Using hot water to remove any chemical residue

ELECTROPLATING

Electroplating Module

PROCESS

Pros Cons

• Produce high quality metallic and glossy appearance

• Not environmental friendly process

• Substrate of SUS, Al, Zn and Mg is relatively low cost

• Cost and time consuming process

• Improved physical properties of metals and extend the metal life

• Plating is not uniform

PROS & CONS

APPLICATION

Jewelry Car Parts Kitchen

Equipment

• Refers to the exposure of the plate after removing the protective film etching region, which in contact with a chemical etching solution to dissolve corrosion

• Resulting on the formation of irregularities or hollow molding effect.

• Divided into two types,

Dry etching: Materials is dissolved when immersed in chemical solution

Wet etching: Materials is sputtered or dissolved using reactive ions or vapor phase etchant

ETCHING

INTRODUCTION

PURPOSE

• To remove material from areas identified by the lithography process Areas of photoresist exposed to light Developing leaves only these areas open Etching removes substrate areas not masked

• To create structures for functional use

• To remove oxide layers below features to allow for motion

PROCESS

Metal store

Cleaning Coating Photo-mech

Developing

Etching Dimensional inspection

Stripping Inspection Packaging

Metal store • Sheet metal from a comprehensive metal store is cut to size

Cleaning • The cut sheet are cleaned to ensure they are chemically clean

Photo-mech • The coated metal plates are placed between multi-image photo-tools and exposed to UV light

Developing • The unwanted photo-resist is developed away leaving the component shape is protected

Etching • Etchant removes unprotected metal under precise control

Dimensional inspection • Etched parts are dimensionally checked against drawing data

Stripping • Photo-resist is removed from the etched component

Inspection • Parts are viewed and inspected

Packaging • Components are packed & dispatched

EQUIPMENT

Dry etching machine

Vacuum plasma etching machine

Pros Cons

• Give natural appearance with high gloss

• Corrosive acid or alkaline liquids is used

• Produce a relatively durable finish • Most of liquids used is hazardous

• Only done periodically • Thus, not environmental friendly process

Manufacturing of printed circuit boards

Manufacture of semiconductor

devices

Used in preparation of metallic specimen

for microscopic observation

APPLICATION

PROS & CONS

MICRO-ARC OXIDATION (MAO)

• Process of generating a high voltage ceramic surface coating is applied in an weak alkaline electrolyte solution where a physical discharge process and electrochemical oxidation occurs.

• Through the electrolytic solution, the electrochemical formation of the anodic film on the surface of metal is existing by spark or arc discharges.

• Resulting in the initiation at potential above the breakdown voltage of growing oxide film.

• The arc and plasma discharges move rapidly across the anode surface.

• As a result, a coating layer, consisting of oxidized forms of the elements of the base metal and electrolyte components, is formed.

INTRODUCTION

PURPOSE

• Forming a porous ceramic coatings of complex

composition. • To enhance wear-resistance. • To improve the corrosion and heat resistance • To produce metals with low dielectric capacity, • Enhancing the light-reflecting and light-absorbing features of

metals.

PROCESS

Pre-treatment

MAO Drying

Process

• The metal need to be treated in the pre-treatment process where all the impurities is removed on the metal surface.

• The metal used as an anode is immersed in environmental friendly alkaline electrolyte.

• Initiation of discharge is provided when the micro arching voltage at which the dielectric breakdown of the oxide film occurred.

• The electrolyte is pumped through a filter and heat exchanger and then introduced into the process chamber with micro bubbles oxygenating the electrolyte.

• The oxide film proceeds as substrate metal oxidation. • Electrolyte additives is such as phosphates and silicate is introduced

into the coatings. • The high voltage supplied to the anode causing the oxide later to

be formed and when critical voltage degree is exceeded, micro arc oxidation process start to occur.

• The oxide layer formed is cooled, dried and finishing process where coloring or sintering take places.

EQUIPMENT

Micro-arc oxidation unit

SEM image for MOA

PROS & CONS

Pros Cons

• Ceramic texture, appearance dull, no high-light products, delicate touch, fingerprint-proof

• Currently restricted color, only black and grey.

• Can used variety of base materials such as Al, Ti, Zn, Zr, Mg, Nb and their alloys.

• Bright color is difficult to achieve

• Simple pretreatment product corrosion resistance

• High cost in power

• Excellent weather resistance

• Excellent thermal performance.

Thermal

• Low thermal conductivity of metals can increase the thermal shock resistance

Electric & Electronics

• Used as insulator film

• Hard coatings for inner areas

Chemical

• Resistance to strong acids and bases.

• Used in chemical and food industries

Mechanical

• Used in lubrication process

• Higher hardness can increase sliding, abrasive and erosive wear resistance

APPLICATION

• This slide presentation is prepared by Research & Development Team, KGC Resources Sdn Bhd

• Any inquiries, feel free to email us at info.kgc00@gmail.com

Thank you