Adhesives

Surface Preparation 210

This class discusses surface factors that affect adhesion, the nature of the different types of surfaces used in adhesive bonding, and the methods of selecting and preparing a surface for adhesive bonding.

  • Difficulty Intermediate

  • Format Online

  • Number of Lessons 18

  • Language English

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Course Outline
  • Objectives
  • The Nature of a Bonded Surface
  • Factors Preventing Successful Adhesion
  • Types of Surfaces
  • Types of Surfaces: Metal
  • Types of Surfaces: Plastic
  • Why Prepare a Surface?
  • Selecting a Surface Treatment
  • Passive vs. Active Surface Treatment
  • Passive Surface Treatment: Physical Methods
  • Types of Physical Abrasive Methods
  • Passive Surface Preparation: Chemical Methods
  • Active Chemical Surface Treatment: Metal Surfaces
  • Active Chemical Surface Treatment: Plastic Surfaces
  • Active Physical Surface Treatment: Plastic Surfaces
  • Determining the Effectiveness of a Surface Treatment
  • Storing Prepared Surface Materials
  • Summary
Objectives
  • Describe a boundary layer.
  • Describe factors that prevent adhesive bonding.
  • Describe types of surfaces.
  • Describe metal surfaces.
  • Describe plastic surfaces.
  • Describe the benefits of preparing a surface.
  • Identify questions that assist in selecting a surface treatment.
  • Distinguish between active and passive surface treatment.
  • Describe passive physical surface treatment.
  • Describe common methods of surface abrasion.
  • Describe passive chemical surface treatment.
  • Describe common active chemical treatment processes for metal surfaces.
  • Describe common active chemical treatments for plastic surfaces.
  • Describe common active physical treatments for plastic surfaces.
  • Describe common methods that determine the effectiveness of a surface treatment.
  • Explain how to store a prepared surface.
Glossary
vocabulary term
Definition

abrasive blasting

Also called grit blasting, the process of removing surface contaminants by forcibly spraying grit onto a surface.

abrasive media

Used in surface abrasion, the materials used to carry and scrape off surface contaminants.

acid descaling

Also called chemical pickling, the process of dissolving oxide and scale from a metal surface.

active chemical surface treatment

The process of removing surface contaminants using chemicals to alter the chemistry of a surface.

active physical surface treatment

The process of removing surface contaminants using physical means of altering the chemistry of a surface.

active surface treatment

The process of removing or controlling surface contaminants by altering the surface chemistry. Active surface treatment is used only when maximum joint strength and performance are required.

adhesive bonding

The joining of two or more materials through the use of adhesives. Material surfaces must be sufficiently prepared for the adhesive to bond effectively.

alloy

A metal consisting of a mixture of two or more materials. One of these materials must be a metal.

anodizing

The process of covering a surface with an oxide film, which helps to prevent surface corrosion. Anodizing is often used to prepare aluminum surfaces.

atmospheric pressure

The weight of the atmosphere or the amount of pressure exerted by the air. During corona discharge treatment, plasma forms at atmospheric pressure.

boundary layer

A layer of contamination that covers a surface. Boundary layers must be removed or controlled for successful adhesion.

chemical erosion

The process of using chemicals to wear away an element or elements. Chemical etching removes surface contaminants through chemical erosion.

chemical etching

The process of removing a layer of contamination on a metal or plastic surface through chemical erosion.

chemical pickling

Also called acid descaling, the process of dissolving oxide and scale from a metal surface.

chemical treatment method

The removal of surface contaminants using chemicals. Chemical treatment methods may or may not alter the chemistry of a surface.

chromating

The process of covering a surface with an oxide layer that chemically reacts to form metal chromates. Chromating is often used to prepare steel, aluminum, and magnesium surfaces.

corona discharge

An unstable plasma created in air at atmospheric pressure. The plasma is created when a spark of high-voltage, high-frequency electricity passes through air between two electrodes.

corona discharge treatment

The process of using a corona discharge to make a surface more receptive to coatings. Corona discharge is a plasma created in air at atmospheric pressure.

dry abrasion

The process of uniformly sanding a surface with an abrasive element, such as sandpaper.

dry abrasive blasting

The process of removing surface contaminants by forcibly spraying fine, nonmetallic material onto a surface.

dry wiping

The process of dusting a surface with a clean cloth.

elastomer

A group of plastics that can stretch and then return to the original shape without permanent deformation. Adhesives do not easily wet elastomer surfaces.

etchant

Substance used in chemical etching. Etchants remove contamination on metal or plastic surfaces by causing chemical erosion.

flame treatment

The process of burning away surface contaminants by forcibly spraying a flame onto a plastic surface.

grit

Abrasive material. Grit is often used in passive physical surface treatment methods.

grit blasting

Also called abrasive blasting, the process of removing surface contaminants by forcibly spraying grit onto a surface.

high pressure water blasting

The process of removing surface contaminants by forcibly spraying water onto a surface.

high surface energy

The tendency of a surface to attract, rather than repel, an adhesive. High surface energy improves an adhesive's wetting ability.

hydrated oxide layer

An oxide layer combined with a water layer. Often, an adhesive must be compatible with a hydrated oxide layer.

inert gas

A gas that does not chemically react with the substance it contacts. Plasma treatment creates plasma in an inert gas.

ionized

Exhibiting a negative or positive charge after gaining or losing one or more electrons.

joint

The point at which two materials are joined together. Insufficient surface preparation weakens a joint.

low surface energy

The tendency of a surface to repel, rather than attract, an adhesive. Low surface energy prevents an adhesive from sufficiently wetting a surface.

metal

A hard, crystalline solid that conducts electricity and heat. Adhesives are often used to bond metal surfaces.

mold

A hollow cavity that holds heated liquid metal or plastic and imparts its shape as the material cools.

mold release agent

Any chemical that is used to help release a molded part from a mold cavity. Mold release agents are often coated onto polymeric composite surfaces used in adhesive bonding.

organic

A material containing carbon and derived from living organisms. Plastic surfaces are organic.

oxide

A chemical compound containing oxygen and one other element. The oxide layer is the main factor in determining the surface treatment for a metal surface.

passive chemical surface treatment

The process of removing surface contaminants using chemicals. This process does not alter surface chemistry.

passive physical surface treatment

The process of removing surface contaminants by physically scrubbing the surface. This approach does not alter surface chemistry.

passive surface treatment

The process of cleaning a surface to remove contaminants. Passive surface treatments neither interact with nor alter the chemistry of a surface.

phosphating

The process of converting a steel surface to iron phosphate. Phosphating improves the corrosion- and wear-resistance of a steel surface.

physical treatment method

The removal of surface contaminants using physical means. Physical treatment methods may or may not alter the chemistry of a surface.

plasma

Ionized gas, or gas that has an electrical charge after being stripped of electrons. Corona discharge treatment creates a plasma.

plasma treatment

The process of creating plasma in an inert gas. Plasma treatment increases surface energy and wetting ability of a plastic surface.

polar surface

An ionized surface that increases the magnetic attraction between the coating and the surface.

polymeric blasting

The process of removing surface contaminants by forcibly spraying hard plastic abrasive material onto a surface.

polymeric composite

A substance composed of plastic and other material or materials. Polymeric composite surfaces are often used to create parts for lightweight vehicles.

primer

A coating applied to a surface to improve adhesion. Primers also protect a prepared surface against recontamination during storage.

prototype

The original test model of a part. Testing prototype joints helps to detect surface changes after adhesion.

reactivity

The susceptibility of a substance to undergo change when exposed to another substance. Active physical surface preparation activates the reactivity of a plastic surface.

scale

Thick oxide coating on a metal surface. Chemical pickling removes scale.

solvent

A chemical used to dissolve another material. Solvents are often used to dissolve surface contaminants.

substrate

The material onto which an adhesive is placed. The surface is the portion of the substrate that directly interacts with the adhesive.

surface

That portion of the substrate with which an adhesive directly interacts to form an adhesive bond. A surface is defined both by the area and depth of the substrate that interacts with the adhesive.

surface abrasion

The process of physically scraping away surface contaminants. Surface abrasion involves passive physical surface treatments.

surface cohesive strength

The internal strength of a surface. Low surface cohesive strength weakens a joint.

surface energy

Measure of the tendency of a surface to repel an adhesive. Low surface energy refers to a surface's repelling tendency, while high surface energy refers to a surface's attracting tendency.

ultrasonic

A frequency above the range of human hearing. Some methods of surface preparation involve vibrating the cleaning solution at ultrasonic frequencies.

ultraviolet light

UV light. Light not visible to the naked eye because it consists of wavelengths shorter than those of visible light. Exposing a plastic surface to UV light creates a polar surface.

UV light

Ultraviolet light. Light that is invisible to the naked eye because it consists of wavelengths shorter than those of visible light. Exposing a plastic surface to UV light creates a polar surface.

vapor honing

The process of removing surface contaminants by forcibly spraying grit suspended in a solvent onto a surface.

water break test

The process of pouring water onto a surface to determine whether oil remains on the surface. When water is poured onto an oily surface, the water forms beads.

weak boundary layer

A layer of contamination that is weakly attached to a surface. Weak boundary layers cause an adhesive to bond with the contaminated layer rather than the surface.

wetting angle

The angle formed between the adhesive and the surface. Comparing the wetting angle with a reference liquid measures the wetting ability of a surface.

wetting angle test

The process of measuring the wetting ability of a surface by comparing the wetting angle with a reference liquid.