The　real　contact　area(RCA)of　randomly　rough　contacts　has　received　a　great　deal　of　attention　because　it　correlates　strongly　with　friction,lubrication,sealing,and　conductivity.Simulations　have　revealed　that　the　RCA　associated　with　deterministic　normal　squeezing　loads　increases　when　tangential　loads　are　also　applied,in　a　phenomenon　called　junction　growth.However,experimental　investigations　of　the　junction　growth　of　randomly　rough　contacts　are　rare.Here,we　used　X-ray　computed　tomography(CT)to　measure　junction　growth　when　two　aluminum　alloy　surfaces　were　in　contact.A　high-resolution　experimental　setup　was　used　to　apply　loads　and　observe　contact　behaviors　at　a　resolution　of　4　μm.The　RCA　and　average　contact　gaps　were　computed　using　a　three-dimensional(3D)geometric　model　constructed　from　gray　CT　images　using　the　Otsu　thresholding　method.The　results　showed　that　the　RCA　increased　as　the　normal　load　increased.The　RCA　increased　by　22.67%after　a　tangential　load　was　applied(junction　growth),and　the　average　gap　decreased　by　14.01%after　a　tangential　load　was　applied.Thus,X-ray　CT　accurately　measured　the　junction　growth　as　a　novel　quantitative　method.