Thermal Spray Coating Technology

요약:

The importance of thermal spraying has risen significantly especially in the past 20 years, because of increasing demands on components.
Thermal Spray Coating involves melting or heating of powder or wire feedstock using special torches, accelerating the particles towards the part to be coated where they impact and cool to form a coating.

Thermal spray processes have gained acceptance and are widely used in different industrial branches. The importance of thermal spraying has risen significantly especially in the past 20 years, because of increasing demands on components.

The combination of structural and surface demands e.g., outstanding strength combined with high corrosion or wear resistance) can often only be met economically by applying coatings. Thermally sprayed wear and/or corrosion protective coatings as well as thermal barrier coatings are examples of this strategy. Additionally, thermal spraying is applied to repair parts. In the standard DIN EN 657, thermal spraying is defined as a process, in which the feedstock is partially or fully melted inside or outside a spraying gun and deposited on a prepared surface.

Usually, the component surface is not melted. The typical coating thicknesses range from 50 μm to 2 mm, but there are also applications with thicknesses of up to 10 mm. Thermal spray processes feature inherent advantages:

• All materials with a liquid phase or sufficient ductility below the decomposition temperature can be applied
• A low thermal stress of the substrate is possible
• There is possibility to deposit coatings on large or locally very limited areas
• There is partial possibility to use equipment onsite

However, in general, there is a weak bond strength between the substrate and the coating; the coatings contain pores. Post treatment (e.g., by remelting) hot isostatic pressing (HIP) or shot peening helps to improve the bond strength and/or decrease the coating porosity. Usually, exact coating thickness is achieved by grinding, which also provide a low surface roughness.

Thermal Spray Coating involves melting or heating of powder or wire feedstock using special torches, accelerating the particles towards the part to be coated where they impact and cool to form a coating. Generally any material without a sublimation point can be deposited using this technique.

Thermal spray can be used to apply high performance surfaces to resist wear, corrosion or heat damage. Thermal Spray Coating can also be applied for special applications such as electrical insulation or conduction, x-ray emission and thermal emission. A common application is build up and repair of worn components.

Types of Thermal Spray Coating

» Premium HVOF Coatings
» Low Pressure Plasma Spray (LPPS) System
» Air Plasma
» Electric Arc Wire
» Wire Combustion
» Powder Combustion



Figure 1: Premium High Velocity Oxygen Fuel Coating (HVOF)

The High Velocity Oxygen Fuel Coating Process (HVOF) is considered the most advanced method of applying hard tungsten or chromium carbide coatings by thermal spray.

Fine powders of these material is deposited at supersonic speeds onto the part being coated, forming exceptionally dense adherent deposits. Typical coating ranges are .003-.015” thick.

Coatings can be ground to mirror finishes using diamond wheels or left unfinished to serve as gripping surfaces. Other hard facing material such as Stellites, Triballoys and bronzes may also be deposited using this technique.

Corrosion resistant materials such as 316 or Hastelloy are also deposited routinely. Below are given some technical information on HVOF applied Tungsten carbide-86:10:4% Cobalt Chrome coating.

Low Pressure Plasma Spray (LPPS) System

Surface Modification Systems Inc. (SMS) a leader in the development of high technology coatings for industry is one of the few job shops in the world with a low pressure plasma spray (LPPS) system.



Figure 2: Low pressure plasma spray (LPPS) system

LPPS allows formation of extremely dense overlays with metallurgical bonding. Coating thicknesses can vary from .005”-.1”. Overlays can include Stellites, carbides, ceramics, nickel and iron based hard facings. This technology is applicable where HVOF and conventional plasma or flame spraying techniques are inadequate.

Testing has revealed that the wear, corrosion and oxidation resistance of these coatings are superior to that of other types of thermal spray. LPPS can be used to solve wear, corrosion and high temperature problems in the valve, pump, medical and aerospace industries.

기술 자료 검색

검색할 어구를 입력하십시오:

검색 범위

본문
키워드

머릿글
요약

Total Materia는 다양한 나라와 규격에 따른 금속학 이미지에 대한 정보를 포함하고 있습니다.

메뉴 표시줄에 특별히 디자인된 금속학 탭을 이용하여, 금속학 데이터가 포함된 관심 재질을 리스트에서 선택하실 수 있습니다.

또한 금속학 데이터는 표준 빠른 검색을 통해 찾을 수 있으며 규격 내 소그룹 페이지를 통해 이용 가능한 관련 자료들이 표시됩니다.

재질명을 '재질'창에 입력하신 후 규격을 알고 계신다면 규격을 선택하고 '검색' 버튼을 클릭합니다.


미세 구조에 대한 일반적인 정보가 관련 관심 재질의 화학 조성과 함께 출력됩니다.


구조의 세부 범위를 보여주는 여러 배율에서의 이미지가 가능하다면 제공됩니다.

다양한 조건을 선택할 수 있으며, '조건 선택' 메뉴를 사용하여 다양한 공정 및 열처리에 따른 금속학 이미지를 보여줍니다.



Total Materia 데이터베이스를 사용해 보실 수 있는 기회가 있습니다. 저희는 Total Materia 무료 체험을 통해 150,000명 이상의 사용자가 이용하고 있는 커뮤니티로 귀하를 초대합니다.