Niobium-based compositions and coatings, niobium oxides and their alloys applied by thermal spraying and their use as an anticorrosive

• US 7,651,731 B2
• Filed: 11/13/2002
• Issued: 01/26/2010
• Est. Priority Date: 09/06/2002
• Status: Expired due to Fees

• Current Assignee: Coppe/Ufrj-Coordenacao Dos Programas de POS Graduacao de Engenharia Da Universidade Federal Do Rio de Janeiro
• Original Assignee: Coppe/Ufrj-Coordenacao Dos Programas de POS Graduacao de Engenharia Da Universidade Federal Do Rio de Janeiro
• Inventors: Goncalves Pereira, Antonio Carlos, Carvalho, Ladimir Jose, Martins Miranda, Luiz Roberto
• Primary Examiner(s): Saeed; Kamal A
• Application Number:
  US10/525,366
• Publication Number:
  US 20060127577A1
• Time in Patent Office: 2,631 Days
• Field of Search: 427/250
• US Class Current: 427/250
• CPC Class Codes: C22C 27/02 Alloys based on vanadium, niobium, or tantalum
• CPC Class Codes: C23C 4/02 Pretreatment of the material to be coated, e.g. for coating on selected surface areas
• CPC Class Codes: C23C 4/04 characterised by the coating material
• CPC Class Codes: C23C 4/08 containing only metal elements C23C4/073 takes precedence
• CPC Class Codes: C23C 4/11 Oxides

Abstract

The novelty proposed herein describes the application of niobium-based compositions and coatings, niobium oxides and their alloys capable of associations with other oxides and alloys by means of the thermal spraying technique for the purpose of an anticorrosive protection in highly corrosive environments, mainly those which present high temperatures, show presence of gases such as H₂S, SO₂, CO₂, as well as organic and inorganic acids, commonly found in industrial centers.

Claims

1. A method of applying a Niobium Oxide coating as an anti-corrosive, the method comprising the steps of:

pre-cleaning a metallic surface that will receive the Niobium Oxide coating;

blasting, with abrasive, to attain a roughness necessary for coating anchoring;

pre-heating the metallic surface; and

applying the coating by thermal aspersion.

2. The method according to claim 1, wherein the Niobium Oxide coating has the following characteristics:

melting point;

1512°

C.;

specific gravity;

4.6 g/cm³;

niobium oxide %;

99.4;

sulphur (ppm);

less than 10;

iron (ppm);

up to 229;

lead (ppm);

less than 1; and

granulometry;

100-400 #Tyler mesh size.

3. The method according to claim 1, including the step of:

applying a 40 Al-60 Nb agglomerate as a pre-layer promoter of adherence between the metallic substrate and the Niobium Oxide layer.

4. The method according to claim 1, wherein parameters for the coating application, by thermal aspersion, are:

oxygen pressure;

from 2.0 up to 4.0 kg/cm³;

acetylene pressure;

from 0.5 up to 1.0 kg/cm³; and

coating deposition rate;

from 5 up to 15.