PCC Coating

Name: PCC Coating
Database: NASA Ames Thermal Protection Materials
Category: Coatings
Composition: Silicon Dioxide, Ludox AS-40, D.I.Water, Silicon Hexaboride
Manufacturer: Wessex, Incorporated
Technical Readiness Level: 7
Last Modified: 2001-10-01

Description:

  • Protective Ceramic Coating (PCC) is a dark gray coating for flexible blanket insulations and other nonvitreous ceramic materials. It may be applied to advanced blankets such as AFRSI, AFRSI-2500, CFBI, and other rigid ceramic substrates which require a high emissivity coating for enhanced radiant properties at elevated temperatures. It is composed of H2O, silica powder, colloidal silica solution, and Silicon Hexaboride (as an emittance agent). It is prepared by ball milling Ludox AS-40, with Cerac S-1061 SiO2, Silicon Hexaboride, and de-ionized water. The coating can be modified with the addition of a solvent and/or binder in order to increase the adhesion characteristics of the system for a specific application. PCC is usually applied to TPS blankets with a 2 to 3 inch bristle brush. The coating has also been sprayed onto fabrics and flexible substrates. The brushing technique tends to provide better coverage of toes and weaves of fibrous material. The amount of coating that should be applied in order to achieve a specific dry weight per unit area should be applied during a one coat procedure. Excessive amounts of coating can severely stiffen a given flexible composite and cause undesirable surface cracks in the coating. The most widely used methods of applications are discussed in the current version of the PCC specification. Applying the coating to blankets which have been previously waterproofed is also addressed. Please consult with the POC to obtain a copy. Thermal exposure to temperatures exceeding 1400¡F (760¡C) will rigidize and increase the durability of thecoating. PCC has survived repeated thermal convective exposure to 2600¡F (1426¡C) on AFRSI-2500 blankets and 3000¡F (1650¡C) on Alumina felts. The emissivity values shown in the properties section were derived from PCC coated samples of Nextel 440. Note how the listed emissivity values for samples that have been exposed to 1400 K are higher than the values derived from the as-processed samples.

Point of Contact:

  • Marc Rezin
  • NASA Ames Research Center
  • mrezin@mail.arc.nasa.gov

Pictures:

Properties at Standard Conditions
SI Units (MKS)
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Property Value Units Uncertainty Source STP Reference Last Modified Additional Data
Additive Areal Weight1 6.58e-01 kg/m^2 3.29e-02 measured assumed/assumed 2 2006-01-05
Emissivity2 9.05e-01 - 4.53e-02 unknown TRUE 1 2006-01-05

Notes:

  • 1. The dry coating weight should be between 0.054 and 0.0775 g/cm^2.
  • 2. Data from PCC coated Nextel 440 cloth.

Property References:

  • 1. D. Kourtides, C. Carol, M.Guzinski, J. Marshall, J. Pallix, J. Ridge, D. Smith, D. Tran: Evaluation of Thermal Control Coatings for Flexible Ceramic Thermal Protection Systems:NASA TM 112199:Jul. 1997:TPSX Ref. #122.
  • 2. Rex Churchward: Specification for the Preparation and Application of Protective Ceramic Coating (PCC) to Ceramic Fabrics and Flexible Insulations:U.S. Patent 5,296,288:NASA Ames:Mar. 1994, Revised- Mar.:TPSX Ref. #123.

General References:

  • 1. D.A. Stewart: Surface Catalysis and Characterization of Proposed Candidate TPS for Access-to-Space Vehicles:NASA TM-112206:Jul. 1997:TPSX Ref. #19.
  • 2. D. Mui, H.M. Clancy: Development of a Protective Ceramic Coating for Shuttle Orbiter Advanced Flexible Reusable Surface Insulation (AFRSI):Ceramic Engineering and Science Proceedings:Jul.-Aug. 1985:TPSX Ref. #35.