GB/T 2998-2015 定形隔热耐火制品体积密度和真气孔率试验方法/Test method for bulk density and true porosity of shaped insulating refractory products
定形隔热耐火制品体积密度和真气孔率试验方法
1 范围
本标准规定了定形隔热耐火制品体积密度和真气孔率测定的术语和定义、原理、设备、试样、试验步骤、结果计算及试验报告。
本标准适用于定形隔热耐火制品体积密度和真气孔率的测定，
2 规范性引用文件
下列文件对于本文件的应用是必不可少的。凡是注日期的引用文件,仅注日期的版本适用于本文件。凡是不注日期的引用文件,其最新版本(包括所有的修改单)适用于本文件。
GB/T 2997 致密定形耐火制品 体积密度、显气孔率和真气孔率试验方法(GB/T 2997-2015，ISO 5017:2013,MOD)
GB/T 5071 耐火材料 真密度试验方法(GB/T 5071-2013,ISO 5018:1983,MOD)
GB/T 10325 定形耐火制品验收抽样检验规则(GB/T 10325-2012,ISO 5022:1979,NEQ)
3 术语和定义
下列术语和定义适用于本文件，
3.1
体积密度 bulk density
ρb
带有气孔的干燥材料的质量与其总体积的比值。
3.2
总体积 bulk volume
Vb
带有气孔的材料中固体物质、开口气孔及闭口气孔的体积总和。
注:表面粗糙度影响总体积测定的准确性。从而影响体积密度测定的准确性。另外,当试样的体积减少到某一极限以下或组织结构(孔径和颗粒)太粗时,体积密度难以精确测得。
3.3
真密度 true density
ρt
带有气孔的干燥材料的质量与其真体积之比值。
3.4
真体积 true volume
带有气孔的材料中固体物质的体积。
3.5
开口气孔 open pores
浸渍时能被液体填充的气孔,气孔率按 GB/T 2997 测定。
注：原则上这些气孔都与大气相通,直接相通或者通过其他气孔相通。表面粗糙度也对开口气孔体积测定的准确度有影响。
3.6
闭口气孔 closed pores
浸演时不能被液体填充的气孔。
3.7
真气孔率 true porosity
显气孔率和闭口气孔率的总和。
3.8
定形隔热制品 shaped insulating product真气孔率不小于45%的定形制品。
4 原理
对规定几何形状的干燥试样,称量其质量并测量其尺寸,计算试样的体积密度。依据试样的真密度(按 GB/T 5071 中规定的方法测定)计算真气孔率。
注:用在液体中浸溃或漫泡的方法测定试样的质量不适用于热耐火制品,因为隔热耐火制品的组织结构疏松,如果用漫泡的方法测定试样质量可引起重大的误差。结果的准确度不需修正,因为称量是在空气中而不是在真空中进行的，
5设备
5.1卡尺或直角钢尺
分度值为0.5 mm。
5.2 电热干燥箱
能控制温度在110℃±5℃.
5.3天平
分度值为 0.1 g。
5.4干燥器
6 试样
6.1 待测的样品(砖或大块)数量按 GB/T 10325 的规定或由相关方协商确定。
6.2 如果测定几批样品,则从每批产品上所取的试样数量应相同,以便统计计算。注:通常,每个样品制取一块试样。每个样品上所取的试样数量也可按该产品的技术条件规定或由有关双方商定。
6.3 试样的各个面应为矩形且对应面平行。每块试样的体积应不小于 500 cm3,棱长应不小于50 mm。试样的各个面应平整以使试样呈平行六面体。沿试样每对相对的面的中心线分别测量四次,各次测量偵之差不应超过 1.0 mm。
6.4 对于用锯切成的隔热砖,要求各面平整且对应面平行,平行度偏差符合 6.3的规定即可用整砖作试样。
7试验步骤
7.1 用卡尺(5.1)测量每块试样的三维尺寸(长度L,宽度b和厚度d),精确至 0.5 mm。应沿每个面的中心线测量,每维尺寸需测量四次,并计算其平均值。
7.2 在电热干燥箱(5.2)中干燥试样,温度控制在(110 ℃±5 ℃),然后在干燥器(5.4)中冷却至室温。称量每块试样的质量,精确至 0.1 g。
7.3 反复干燥、冷却和称量试样,直到恒量。试样在电热干燥箱中至少干燥2h,前后两次连续称量之差不大于其前一次的 0.1%即达到恒量。
7.4 如果需要,按照 GB/T 5071 测定试样的真密度,计算其真气孔率。
8结果计算
8.1 试样的总体积V,按式(1)计算,以立方厘米为单位:
式中:
L、b、d–分别是试样的长度,宽度和厚度,单位为厘米(cm)。
8.2 试样的体积密度ρb按式(2)计算,以克每立方厘米为单位:
式中:
m –干燥试样的质量,单位为克(g);
Vb–试样的总体积,单位为立方厘米(cm3)。
8.3 体积密度以g/cm3或kg/m3表示,保留三位有效数字。
8.4 试样的真气孔率π,按式(3)计算,以%表示:
式中:
ρb–试样的真密度,单位为克每立方厘米(g/cm3)；
ρt–试样的体积密度,单位为克每立方厘米(g/cm3)(见 8.2)。
9试验报告
试验报告应包括下列内容:
a)试验单位名称;
b)试验人员;
c)试验日期;
d)执行标准号,即“按 GB/T 2998 试验”;
e)委托单位名称;
f)试样的名称、牌号、批号;
g)每批样品的整砖数或试块数;
h)每批试样试验结果的单值和平均值。
Test method for bulk density and true porosity of shaped insulating refractory products
1 Range
This standard specifies the terms and definitions, principles, equipment, samples, test procedures, calculation of results and test reports for the determination of bulk density and true porosity of shaped heat-insulating refractory products.
This standard is applicable to the determination of bulk density and true porosity of shaped heat-insulating refractory products.
2 Normative reference documents
The following documents are essential for the application of this document. For dated references, the date-only version applies to this document. For undated references, the latest version (including all amendment orders) applies to this document.
Test method for bulk density, apparent porosity and true porosity of compact shaped refractory products GB/T 2997 (GB/T 2997-2015, ISO 5017:2013,MOD)
GB/T 5071 refractories true density test method (GB/T 5071-2013,ISO 5018:1983,MOD)
Rules for Sampling Inspection of GB/T 10325 Shaped Refractory Products (GB/T 10325-2012,ISO 5022:1979,NEQ)
3 Terms and definitions
The following terms and definitions apply to this document,
3.1
Bulk density
ρb
The ratio of the mass of a dry material with pores to its total volume.
3.2
Total volume bulk volume
Vb
The total volume of solid material, open porosity and closed porosity in a material with pores.
Note: Surface roughness affects the accuracy of total volume measurement. Thus, the accuracy of volumetric density measurement is affected. In addition, when the volume of the sample is reduced below a certain limit or the microstructure (pore size and particles) is too coarse, the bulk density is difficult to measure accurately.
3.3
True density
ρ t
The ratio of the mass of a dry material with pores to its true volume.
3.4
True volume
The volume of solid material in a material with pores.
3.5
Open pores
Pores that can be filled with liquid during impregnation, porosity measured in GB/T 2997.
Note: In principle, these pores are communicated with the atmosphere, directly or through other pores. Surface roughness also affects the accuracy of porosity measurement.
3.6
Closed pores
Pores that cannot be filled with liquid during immersion.
3.7
True porosity
The sum of apparent porosity and closed porosity.
3.8
Shaped thermal insulation products with a true porosity of not less than 45%.
4 Principles
The bulk density of the dry sample with specified geometry is calculated by weighing its mass and measuring its size. The true porosity is calculated based on the true density of the sample (determined by the method specified in GB/T 5071).
Note: Measuring the quality of the sample by dipping or bubbling in the liquid is not suitable for hot refractory products, because the structure of the insulated refractory products is loose, and if the sample quality is determined by bubbling method, it can cause significant errors. The accuracy of the results does not need to be corrected because the weighing is carried out in air rather than in a vacuum,
5 Devices
5.1 calipers or right Angle steel ruler
The index value is 0.5 mm.
5.2 Electric drying oven
The temperature can be controlled at 110℃±5℃.
5.3 Balance
The index value is 0.1g.
5.4 Dryer
6 Sample
6.1 The quantity of samples (bricks or blocks) to be tested shall be determined according to GB/T 10325 or by the parties concerned.
6.2 If several batches of samples are tested, the same number of samples shall be taken from each batch for statistical purposes. Note: Usually, one sample is made for each sample. The number of samples to be taken from each sample may also be specified in accordance with the technical conditions of the product or agreed by the parties concerned.
6.3 Each face of the sample shall be rectangular and parallel to the corresponding face. The volume of each sample should not be less than 500 cm3, and the edge length should not be less than 50 mm. Each face of the sample should be flat so that the sample is parallelepiped. Measurements are made four times along the center line of each opposite pair of faces of the sample, and the detection difference of each measurement should not exceed 1.0 mm.
6.4 For the heat-insulating brick cut by sawing, each side is required to be flat and the corresponding side is parallel, and the parallelism deviation can be used as a sample in accordance with 6.3.
7 Test Procedure
7.1 Measure the three-dimensional dimensions (length L, width b and thickness d) of each sample with a caliper (5.1) accurate to 0.5 mm. Measurements should be made along the center line of each face, and the dimensions should be measured four times per dimension and their average values calculated.
7.2 Dry the sample in an electric drying oven (5.2) at a temperature controlled at (110 ° C ±5 ° C) and then cool to room temperature in a dryer (5.4). Weigh the mass of each sample, accurate to 0.1 g.
7.3 Dry, cool and weigh the sample repeatedly until it is constant. The sample is dried in the electric drying oven for at least 2h, and the difference between the two consecutive weighing is not greater than 0.1% of the previous one to reach the constant amount.
7.4 If necessary, measure the true density of the sample according to GB/T 5071 and calculate its true porosity.
8 Result Calculation
8.1 The total volume V of the sample is calculated according to formula (1), in cubic centimeters:
Formula:
L, b, d– are the length, width, and thickness of the sample, respectively, in centimetres (cm3).
8.2 The bulk density ρb of the sample is calculated according to formula (2), in grams per cubic centimeter:
Formula:
m — the mass of the dried sample, expressed in grams (g);
Vb- The total volume of the sample, in cubic centimeters (cm3).
8.3 Bulk density is expressed in g/cm3 or kg/m3, with three significant digits reserved.
8.4 The true porosity of the sample π is calculated according to formula (3), expressed as % :
Formula:
ρb— the true density of the sample, in grams per cubic centimeter (g/cm3);
ρt– The bulk density of the sample, in grams per cubic centimeter (g/cm3)(see 8.2).
9 Test Report
The test report shall include the following:
a) Name of the test unit;
b) test personnel;
c) Test date;
d) Execution standard number, “Test according to GB/T 2998”;
e) Name of the entrusting unit;
f) Name, grade and lot number of the sample;
g) The number of whole bricks or test blocks in each batch of samples;
h) Single values and average values of test results for each batch of samples.
